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MOTOR TRANSFOK 

CORPS 



EXE< UTH K DH ISIOIN 
T«AI\IN<; BUANCH 



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"WJ0 




Instructors' Guide 



MECHANICS' 
SECTION 

COMPANY 
MECHANIC" COURSE 





WASHINGTON, D.C 

No«rinb«'r 1«>I« 






Glass 
Book 



_i f\ O . 




COMPANY MECHANICS' 
COURSE 

OF THE 

MOTOR TRANSPORT CORPS 



Inspection Section Trouble Shooting Section 

Chassis Section Carburetor Section 

Engine Section Motor Cycle Section 

Ignition Section M. T. C. Administration 



LENGTH OF COURSE, SIX WEEKS 



Form MTC— 433 






LIBRARY OF CONGRESS 
RECEIVED 

CCT2"i:"1923J 



DOCUMENTS DIVISION 



Company Mechanics' Course — Index 



Page 1 



MOTOR TRANSPORT CORPS 
Company Mechanics' Course 

INDEX 

Inspection Section 



Lecture 

Lecture 



I 
II 



Cleaning and Lubrication 
Repair System, A.E.F. 



Chassis Section 



Lecture I Dismantling 
Lecture II Springs and Brakes 
Lecture III Clutch 
Lecture IV Transmission 
Lecture V Differential 

Quiz Questions 



Engine Section 



Lecture 


I 


Principles of Engine 


Lecture 


II 


Cylinders and Valves 


Lecture 


III 


Compression 


Lecture 


IV 


Bearings 


Lecture 


V 


Lubrication 


Lecture 


VI 


Cooling System 


Lecture 


VII 


Camshaft and Crankshaft 
Quiz Questions 



Ignition Section 



Lecture I Electrical Equipment 
Lecture II Magnetos 
Lecture III Battery Ignition 
Lecture IV Generators 

Quiz Questions 



Trouble Section 



Lecture I Engine Trouble 
Lecture II Test Questions 



Lecture I 
Lecture II 
Lecture III 



Carburetor Section 



The Carburetor 
Vacuum Tank 
Governors 
Quiz Questions 



CMC 



Company Mechanics' Course — Index 



Page 2 



Motorcycle Section 

Lecture I Engine 
Lecture II Clutch and Transmission 
Lecture III Road Troubles 
Lecture IV Parts and Repairs 
Quiz Questions 

Administration Section 

Lecture I Accountability and Responsibility 

Lecture II Requisitions 

Lecture III Forms and Correspondence 

Lecture IV Allotments, Compensation, Hygiene 

Lecture V Military Law 



CMC 



GENERAL STATEMENT 

DIRECTIONS FOR INSTRUCTORS 

Underlying all successful instruction must be the realization on the part of 
each man called upon to teach in any subject that all instruction is given for 
the student, not for the instructor. Obviously, then, the success of a teacher 
must be measured by the amount of his teaching which is converted into work- 
ing knowledge by his students. Thus the job for every member of the in- 
structing staff at every school is to put his information across so that the 
members of the class get it and are able to use it. 

The results obtained in frequent quizzes, oral test questions, or the per- 
formance of duties by the student, which require the application of material 
taught, are the fundamental measures of the success of the instructor in his 
work. Too much - emphasis should not be placed on set written examinations, 
for a great deal of information may be acquired and used in a poll parrot 
manner, allowing a man to get high rating on a written examination, but a 
very low rating on any examination in which the student must apply the 
knowledge obtained in class room to the performance of a definite task. 

The instructor should also bear in mind that men learn most things through 
one, or more, of three senses: hearing, sight and touch, and that that instruc- 
tion will be the most successful which permits the student to learn in the most 
ways. Furthermore, some men learn best by hearing, others, by touch, and 
still others by sight, so that no one method can be used with maximum suc- 
cess for all. 

Having the foregoing facts in mind, every instructor, in preparing his work 
for class presentation, should plan to use, to the fullest possible extent, in 
the class, pieces of equipment, such as: rifles, pack equipment, parts of vehicle 
mechanism, such as axles, carburetors, spark plugs, or even whole chasses, if 
requh'ed, etc., etc. He should also use blackboards as much as possible for 
sketches, diagrams, definitions, etc., and should, so far as possible, insist that 
each student keep a note book in each subject, which must be neat in appear- 
ance and accurate in their statements. This will necessitate their inspection 
periodically, which should be done by the instructor or his assistants. 

It will be seen that certain lectures are much shorter than would be re- 
quired to fill the entire periods allotted to them. This is done purposely so 
that there will be an opportunity for the instructor to make up for lost time, 
occasioned by inspections, etc., etc.; or an opportunity for quizzes, special 
lectures, and such other work as the instructor may desire. 

It will also be seen in the course for Motor Transport Company Mechanics 
that in places a four-hour period is devoted to certain lectures. This is done 
because the company mechanic must be a skilled workman and it is not enough 
for him to be informed on a subject; he must also be able to perform certain 
duties. The long lecture period permits reiteration, discussion and repeated 
demonstration on the part of the instructor, so that the student will get all 
details and be able to use his information. The instructor should use all his 
ability to put his ideas across in as many ways as possible to be sure that his 
class gets them thoroughly. 

Instructors must look well to the discipline of their classes. Insistence 
should be placed on all students sitting in proper attitudes during class, and 
no lounging or otherwise careless appearance permitted. When the instructor 
enters the room, all students should rise and remain standing until ordered to 

CMC 



General Statement Page 2 

be seated. They should also rise when an officer enters the room and remain 
standing until otherwise directed. In short, strict military discipline should 
be insisted upon at all times by the instructor, and he should be especially 
careful that all his acts are also guided by the same precepts. 

General Statement 

The lectures in this book are designed for the use of the instructors in 
the various subjects, and are written from that standpoint, following the cur- 
riculum outline in detail. 

The material is put in this form for the use of instructors so that training 
at all schools may be uniform. Copies of this book are not to be used for 
student's text books, and where any of the material contained in this book is 
desired for students' use it is expected that it will be reproduced by mimeo- 
graph or otherwise. 

The lectures are not to be read to the students, but are to give the instruc- 
tors the subject matter to be covered, as well as the method of presentation. 

The material given under Exercises is written in lecture form but is to be 
covered by informal discussion, or otherwise, as the instructor may feel to 
be desirable. 

Under quizzes and written examinations are given typical questions, not 
formal examinations as such. It is expected that the instructor will use such 
of the questions as he may wish for his work, but the main intent in setting 
down the questions is to give the instructor a standard of values by the aid of 
which he should be able to make up his own questions as need arises. 

It is planned to issue bulletins on training activities once a month, for the 
use of instructors at all M. T. C. training camps. These bulletins will be sent 
in quantities to the Commanding Officers of all M. T. C. Training camps, for 
distribution, to the instructing personnel. 

It will be well for instructors who are teaching mechanical subjects to se- 
cure the Instructor's Guide for Company Mechanics' Course as there are many 
details of the vehicle mechanism and diagrams that will be helpful in any work 
of that character. 

No lectures are written on Military Instruction as the plan is to follow the 
reference books closely and have only informal lectures, recitations and 
quizzes. 

Where lectures are prepared for periods not stated as lecture periods in the 
curriculum, it is designed that the material covered by the lecture will be 
given in an informal way during the period assigned for the work. 

Some lectures will be found to be longer than others, and some will be 
found too short to cover the entire period assigned. This arrangement is 
made purposely to permit leeway to compensate for the personal equations 
of the various instructors, as well as to allow for hours lost or shortened by 
various unforeseen circumstances. Where spare time is provided by this means 
it is to be used in bringing up the work, if behind schedule, or for review or 
quiz, if the work is on schedule. 

Motor Truck Drivers 

Instructors will become familiar with the duties of the truck driver and use 
every effort to impress upon such students just what their duties are and 
especially what they ai-e not to do. It must be borne in mind that the driver 

CMC 



General Statement Page 3 

does only the most elementary work on the truck, such as oiling and greasing, 
tightening loose bolts and nuts, changing spark plugs, filling the radiator, 
tightening loose wires, draining the carburetor, etc. He makes no actual re- 
pairs of any magnitude on the motor, or vehicle, except under the direction of 
the company mechanic. In view of the foregoing, the instruction should be 
confined to making the driver familiar with the construction of his vehicle 
and the relation of its parts, but not technically proficient in anything but the 
most minor repairs. Time may well be spent in training him to diagnose 
motor troubles by their symptoms, together with an understanding of their 
causes, so that he may know just what the trouble is, the seriousness of letting 
it go unattended, and the probable time required to make the repairs. Train- 
ing of truck drivers must be restricted by the foregoing consideration. 

Motor Car and Cycle Drivers 

Motor Cars and Cycles operate as independent units, therefore the drivers 
must be taught not only the general mechanism, etc., of the vehicles, but also 
the road repairs and adjustments which are commonly made on vehicles by 
skilled operators. It is often impossible to get a mechanic for this work and 
the driver must be able to make repairs of such character as will be perma- 
nent, so the training of such men in maintenance, as well as driving, must be 
of a thorough nature. 

Military Courtesies 

It is designed that all students should be instructed in military courtesy 
and all commanding officers and senior instructors should have copies of the 
pamphlet on "Military Courtesies" published by the Training Branch, M. T. C, 
and see that all students are instructed in conformity with the directions 
therein contained. 

The fact that an enlisted man completed a course in an M. T. C. School 
shall be recorded under "Remarks" on his Service Record, stating the course 
completed, the date and the general average of his work. 

M. T. C. Training Publications 

The following material may be obtained in quantities as desired by applica- 
tion to the Chief, Training Branch, Motor Transport Corps, Washington, D. C. 
A. Report Forms for Use in M. T. C. Courses. 

1. Motor Transport Company Officers' Course, Forms M. T. C.-289 
and M. T.-290. 

2. Motor Transport Company Truckmasters' Course, Forms M. T. 
C.-291 and M. T. C.-292. 

3. Motor Truck Drivers' Course, Forms M. T. C.-293 and M. T. C- 
294. 

4. Motor Car Drivers' Course, Forms M. T. C.-295 and M. T. C- 
296. 

5. Motor Cycle Company Officers' Course, Forms M. T. C.-297 and 
M. T. C.-298. 

6. Motorcycle Drivers' Course, Forms M. T. C.-299 and M. T. C- 
300. 

7. Motor Transport Company Mechanics' Course, Forms M. T. C- 
301 and M. T. C.-302. 

CMC 



General Statement Page 4 

B. Tables of instructional personnel for schools of different sizes. 

C. Tables of equipment for schools of different sizes. 

D. Blank diplomas for awarding to students in officers' courses at the com- 
pletion of their courses. 

E. M. T. C. Curriculum of Field Service Training. 

F. Tentative Manual of Training of the Motor Transport Corps. 

G. Instructors' Guide for Motor Transport Company Officers' Course. 

H. Instructors' Guide for Motor Transport Company Non-commissioned 
Officers' Course. 

I. Instructors' Guide for Motor Transport Company Drivers' Course. 

J. Instructors' Guide for Motor Car Company Drivers' Course. 

K. Instructors' Guide for Motor Cycle Company Officers' Course. 

L. Instructors' Guide for Motor Cycle Company Drivers' Course. 

M. Instructors' Guide for Motor Transport Company Mechanics' Course. 

N. Curriculum and Lectures for the M. T. C. Administrative Officers' 
Course. 

O. Curriculum and Lectures for the M. T. C. Company Clerks' Course. 
P. Course in Military Courtesies. 



CMC 



Schedule of Classes 



COMPANY MECHANICS' COURSE 

Schedule of Classes 

On the following pages is a schedule of hours of classes for the subjects 
comprising the course for Company Mechanics. The work is divided into 
six blocks, each of one week's duration, and the plan is to start the class in 
six groups, one group on the work of each of the weeks, rotating the groups 
at the close of each week. 

The seeming difficulty of new men starting work on subjects requiring 
previous knowledge and skill is to be taken care of by a preliminary exami- 
nation and trade test of each man, after which he is to be assigned in ac- 
cordance with his ability. In such cases, it is assumed that men of previous 
experience and ability will not be required to spend the full six weeks at the 
work, but will be given additional training only in those subjects in which 
they are deficient. 



CMC 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

FIELD SERVICE TRAINING 

COMPANY— MECHANICS'— COURSE 

LENGTH— SIX WEEKS 





FIRST WEEK— Chassis Section 




Day 


i> tO 8 00 S. 00-9. 00 


9.00-10.00 


10.00-11.00 


11.00-12.00 


1 


,„,„„,_, t-. ,i, I Technical Lecture Shop Practice Shop Practice 
iniantry Drill | Chassis Exercise I Chassis Exercise II Chassis Exercise III 


2 


t t l t\ ii 1 Shop Practice 
Infantry Drill | Chassis Exercise y 


3 


T , , r, -I. 1 ' Shop Practice 
Infantry Drill | Chassis Exercise VII— Contd. 


4 


T , . -n-ii 1 Shop Practice 
Infantry Drill | Chasais Exe ^ dBe iX-Contd. 


5 


T„f „.„, n-.n" 1 Shop Practice Technical Lecture Shop Practice 
intantry Drill | C hassis Exercise IX Contd. | Chassis Exercise X Chassis Exercise XI 


6 


T t n -n 1 Shop Practice Technical Lecture Shop Practice 
iniantry Drill | Chassis Exercise XI— Contd. Chassis Exercise XII I Chassis Exercise XIII 




SECOND WEEK— Engine Section 


7 


r„f»„*„, n_;ii 1 Technical Lecture Shop Practice 
intantry Drill | Engine Exercise I | Engine Exercise II 


8 


T „ f „„ t „, t-. -n 1 Shop Practice Technical Lecture 
iniantry Drill | Engine Exercise VI Engine Exercise VII 


9 


Infantrv Drill 1 Shop Practice Technical Lecture . 1 Shop Practice 

Engine Exercise VIII — Contd. Engine Exercise IX Engine Exercise X 


10 


1, ,- „, n^iii 1 Technical Lecture Shop Practice 
iniantry Drill | Engine Exercise XIII Engine Exercise XIV 


11 


Iniantry Drill 1 v Sho P/ ractice vv 
3 I Engine Exercise XV 


12 


Infantry Drill 1 -, . ?. hop Pra £if „ . . 
* Engine Exercise XV — Contd. 




THIRD WEEK— Ignition Ssction 


13 


Infantry Drill 1 Technical Lecture Shop Practice 

1 Ignition Exercise I Ignition Exercise II 


14 


i„f.„,_, rir^ii 1 Technical Lecture Shop Practice 
iniantry Drill | Ignition Exercise III Ignition Exercise IV 


15 


Infantry Drill 1 Technical Lecture Shop Practice 

Ignition Exercise V Ignition Exercise V I 


16 


Infantrv Drill 1 Technical Lecture Shop Practice 

Ignition Exercise VII — Contd. Ignition Exercise VIII 


17 


Infantry Drill 1 , ... #hop ■ Pra ^ I i c r V r tA 

Ignition Exercise VIII — Contd. 


18 


Infantry Drill 1 T Shop Practice 

Ignition Exercise X 




FOURTH WEEK— Inspection and Carburetor Section 


19 


Infantry Drill 1 . Technical Lecture 

Inspection Exercise I 


20 


Infantry Drill 1 . Sb °P ft ? ct V* 

Inspection Exercise II — ConUl. 


21 


Infantrv Drill 1 Snop Practice 

Inspection Exercise III — Contxl. 


22 


Infantrv Drill 1 Technical Lecture Shop Practice. 

Carburetor Exercise I Carburetor Exercise II 


23 


Infantrv Drill 1 Shop Practice Technical Lecture 

Carburetor Exercise II — Contd. Carburetor Exercise III 


24 


Infantrv Drill 1 Technical Lecture Technical Lecture 

Carburetor Exercise V Carburetor Exercise VI Quiz 




FIFTH WEEK— Trouble Shooting Section 


25 


Infantry Drill 1 „ , , R ° ad Exercise 

1 Trouble Shooting Exercise 1 


26 • 


Infantry Drill 1 Road Adjustments and Repairs 
1 Trouble Shooting Exercise III 


27 


Infantry Drill 1 „ , . S |^P Practice . v 
1 Trouble Shooting Exercise V 


28 


Infantry Drill 1 „ ' Shop Practice 

1 rouble .shooting Exercise \ III 


29 


Infantry Drill 1 _ , , S h. P Practice 

Trouble Shooting Exercise X 


30 


Infantry Drill 1 „ . . Shop Practice 

Trouble Shooting Exercise XII 




SIXTH WEEK— Motorcycle Section 


31 


Infantry Drill 1 Technical Lecture ) 
1 Motorcycle Exercise i( 


32 


Infantry Drill 1 ., . fhop Practice j 

Motorcycle Exercise II — Cdntd. 


33 


Infantry Drill 1 ., , Sno P, Practice 

Motorcycle Exercise I\ 


34 


Infantry Drill 1 Technical Lecture 

Motorcycle Exercise V 


35 


Infantry Drill 1 ... fhop Practice 

1 Motorcycle Exercise \ 1 — I onto. 


36 


Motorcycle Exercise VIII 













MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION— TRAINING BRANCH 

FIELD SERVICE TRAINING 

COMPANY— MECHANICS'— COURSE 

LENGTH — SIX WEEKS 



FIRST WEEK — Chassis Section 



Day 


1.00-2.00 2.00-3.00 


3 00-4.00 


4 00-5.00 


6.30-10.00 


I Shop Practice technical lecture 
1 Chassis Exercise III— Contd. Chassis Exercise I\ 


Administration 
Exercise I 


' 1 Shop Practice Technical Lecture Shop Practice 
2 Chassis Exercise V— Contd. 1 Chassis Exercise \ I 1 Chassis Exercise \ 11 


Night Driving 


, | Shop Practice 1 Technical Lecture Shop Practice 
3 IchassisExerciseYII, Contd. | Chassis Exercise Mil 1 Chassis Exercise I\ 


and 


Shop Practice 
4 Chassis Exercise IX — Contd 


Trouble Shooting 


Shop Practice 
5 Chassis Exercise XI — Contd 


by 


. 1 Shop Practice 1 Shop Practice 1 Inspection 

6 IChassisExerciseXIII.Cont.l Chassis Exercise XIV | Chassis Exercise X\ 


Assignment 


SECOND WEEK— Engine Section 


" - 1 Technical Lecture 1 Shop Practice Technical Lecture 
Engine Exercise III Engine Exercise IV I Engine Exercise \ 


Administration 
Exercise II 


Shop Practice 
8 Engine Exercise VIII 


Night Driving 


Technical Lecture | Shop Practice 
9 Engine Exercise XI I Engine Exercise XII 


and 


Shop Practice „ Shop tract ice 
10 Engine Exercise XIV— Contd. Engine Exercise X\ 


Trouble Shooting 


Shop practice 
11 Engine Exercise XV — Contd. 


by 


,„ 1 Shop Practice 1 ,,„„■ YVT 1 Technical Lecture 
12 Engine Exercise XV— Contd. Exercise X\ I | Final Examination 


Assignment 


THIRD WEEK— Ignition Section 


Shop Practice 
'"* Ignition Exercise II — Contd. 


Administration 
Exercise III 


Shop Practice 
11 Ignition Exercise IV — Contd 


Night Driving 


_- 1 Shop Practice 1 Technical Lecture 
10 Ignition Exercise VI — Contd. Ignition Exercise VII 


and 


Shop Practice 
Ib Ignition Exercise VIII — Contd. 


Trouble Shooting 


1 Shop Practice Technical Lecture 
11 Ignition Exercise VIII — Contd. Ignition Exercise IX Final Exam. 


by 


„ Shop Practice 
*° Ignition Exercise X 


Assignment 


FOURTH WEEK — Inspection and Carburetor Section 


Shop Practice 
la Inspection Exercise II 


Administration 
Exercise IV 


Shop Practice 
•^ Inspection Exercise III 


Night Driving 


Technical Lecture 
- 1 Inspection Exercise IV 


and 


„ 2 Shop Practice 

Carburetor Exercise II — Contd. 


Trouble Shooting 


2 o Shop Practice 

• Carburetor Exercise IV 


by 


24 


Assignment 


FIFTH WEEK— Trouble Shooting Section 


„. | Road Exercise 1 Administration 
ia Trouble Shooting Exercise II 1 Exercise \ 


9fi Road Adjustments and Repairs 
JD Trouble Shooting Exercise IV 


Night Driving 


„_ Shop Practice 

Trouble Shooting Exercise XI 


and 


„ a Shop Practice 

e ° Trouble Shooting Exercise IX 


•Trouble Shooting 


2q Shop Practice 

Trouble Shooting Exercise XI 


by 


30 


Assignment 


SIXTH WEEK— Motorcycle Section 


1 Shop Practice 1 Administration, 

Motorcycle Exercise II Exercise \ I 


«.-, Technical Lecture 

Motorcycle Exercise III 


Night Driving 


o. Shop Practice 

** Motorcycle Exercise IV— Contd. 


and 


o. Shop Practice 

Motorcycle Exercise VI 


Trouble Shoolin 


o- Technical Lecture 

Motorcycle Exercise VII 


by 


ne Shop Practic 

°° Motorcycle Exercise VIII— Contd. 


Assignment 



*See Trouble Shooting Exercises II and VII for Night Driving Repairs. 



Inspection — Lecture I Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
INSPECTION DIVISION 

LECTURE I 

Cleaning and Lubrication 

In cleaning the truck, the duties of the driver and assistant driver are as 
follows: 

1. Cleaning Entire Truck. 

Driver is responsible for condition of entire truck, but personally cares for 



the Power Plant, including — 


1. 
2. 
3. 


Engine proper 
Cooling System 
Carburetor 


4. 
5. 


Ignition 
Generator 


6. 


Dash Instruments 


7. 


Engine Controls 


Assistant Driver is responsible for- 


1. 


Clutch 


2. 


Transmission 


3. 


Drive Shafts 


4. 


Rear Axle 


5. 
6. 


Rear Springs 
Brake Mechanism 


7. 


Rear Wheel 


8. 


Front Axle 


9. 
10. 


Front Springs 
Front Wheels 


11. 


Hood 


12. 


Fender 


13. 


Body 


Notc- 
parts. 


-All grit, sand and mud must 


2. Li 


brication Schedule. 



Number of places given for Liberty Class B trucks, other trucks in pro- 
portion. 

Daily 

1. Fill crank case to proper level. 

2. Fan bearing oil, one grease plug. 

3. Water pump, heavy grease, two cups. 

4. Starting crank, one grease cup. 

5. Grease steeling connections, four grease cups. 

6. Grease steering knuckles, two oil plugs. 

CMC 



Inspection — Lecture I Page 2 

7. Oil spark throttle rod sockets and joints, thirteen places. 

8. Clutch bearing trunnion, one oil plug. 

9. Clutch case bearing, one oil plug. 

10. Oil spring shackles, eight oil wells. 

11. Oil brake rod clevises, twenty clevises. 

12. Oil wells on equalizer and intermediate brake bars, six wells. 

13. Grease # cups on rear axle brake shaft, eight cups. 

14. Oil brake shoe equalizer pine, sixteen, eight for each rear wheel in- 
side brake drum. 

Weekly 

1. Drain oil from crank case, wash out with kerosene, refill to proper 
level. 

2. Wheel bearing grease, all four wheels. 

3. Grease steering gear case, one plug. 

4. Transmission, fill to level. 

5. Fill universal joints, four. 

6. Differential, fill to level. 

7. Two drops oil in magneto, two places. 

8. Two drops oil in generator, two places. 

Notes : 

Use only clean new oil. 

Do not fill self oiling wells on Liberty Trucks higher than X A inch below 
top of wick tube. 

Turn up all grease cups until grease feeds through freely and shows yellow 
exuding from the joints. 

This forces out all dirt from bearings. Wipe off all excess oil and grease. 
Refilled grease cups must be given at least three turns. 

3. Inspect radiator, gasoline tank, and all reserve tanks provided, to make 
sure they are properly filled. 

Inspect complete equipment and report breakage, shortage and repairs 
needed to Assistant Truckmaster. 

1. Tools 

2. Supplies 

3. Equipment. 

4. When the cleaning is done in a formal way, as soon as the duties are 
completed the driver will report to Assistant Truckmaster immediately. 

5. Truckmaster and Assistant Truckmaster should pass around trucks 
during the procedm*e and see that the work is being done properly. 

6. Assistant Truckmaster should report to Truckmaster as soon as alL 
trucks in his section are ready for inspection. 

7. Ti'uckmaster calls company to attention, receives reports from each 
section verbally, makes notes on condition, breakage, shortage and repairs 
needed on each truck. Then upon orders of Company Commander dismisses 
the company. 

It may be well at this time to say that the body and running gear should be 
washed down thoroughly at every opportunity especially where soft mud is on 
the wheels or metal parts, owing to the fact that if this mud should be al- 
lowed to become hard it is very much more difficult to remove. It is not alone 
important to remove that mud which is visible but the man washing the car 

CMC 



Inspection — Lecture I Page 3 

should climb in, clean every conceivable place where dirt could possibly ac- 
cumulate. At times it will be necessary to remove greases, road oils, etc., 
with gasoline. It is very easy for an inspector who is thoroughly experienced 
to locate almost instantly those parts which have been neglected. After a car 
has been thoroughly cleaned the different units that we mentioned a short 
while ago are thoroughly cleaned using kerosene and air if possible or what- 
ever cleaning materials that are on hand under the circumstances. The en- 
gine should be thoroughly washed down removing all grit and sand from not 
only the moving parts but others also. All parts that are plate or metal finish 
should be retained to that standard. The electrical instruments and other im- 
portant motor auxiliaries such as the carburetor, etc., should be thoroughly 
cleaned in the same manner. The other units, particularly the clutch, trans- 
mission, drive shafts, rear construction, springs, brake mechanism and wheels 
should receive that attention which will enable them to function properly and 
therefore eliminate the unnecessary replacement of parts and incidentally pro- 
long the life of the car. The daily and weekly schedules are to be followed 
very closely and it is the duty of the inspector to see that all grease cups are 
well filled as often as prescribed. If the proper lubrication of the car is fol- 
lowed in detail, there will be no necessity of oil running out through the rear 
construction onto the brakes which in many cases is responsible for accidents, 
and I could mention a number of other cases where too much oil is almost as 
bad as none at all. 



CMC 



LUBRICATION CHART 
CLASS B TRUCK 



A DAILY 
B 250MlLEiT 




D-f 1 



»-[ 



-I: 



SPRINC bolt na oa RESERVOIR wi 
ENGINE OH 

[SPRING LEAVES, SEPARATE LEAVES AND 
[SPREAD WITH GRAPHITE AND OIL 

DISTRIBUTOR SHAH. GIVE GREASE CUP 

TWO TURNS 

STEERING CONNECTING TUBE SCREW. 
DOWN CUP UNTIL GREASE OOZES OUT 
WHEEL REMOVE CAP AND OUTER 
BEARING PACK HUB WITH GREASE 
[WHEEL CLEAN OUT AND WASH HUB AND' 
BEARINGS WITH KEROSENE PACK WITH 
[FRESH GREASE 

STEERING KNUCKLE. FILL OIL RESER 
VOIR WITH ENGINE OIL 
STEERING CROSS ROD. FILL OIL CUP' 
WITH ENGINE OIL 

WATER PUMP. TWO GREASE CUPS 
SCREW THEM DOWN TWO TURNS 

MAGNETO. TWO OIL WELLS. TWO DROP! 
OF ENGINE OIL IN EACH 

SPARK ADVANCE LINKAGE SEVE 

PLACES. OIL WITH ENGINE OIL 

OIL GAUGE. INSPECT OIL LEVEL 

CRANK CASE. ADD ENGINE OIL IF LESS 

THAN HALF FULL 

ENGINE. DRAIN OUT OLD OIL FOUR 

PLUGS, AND REFILL WITH FRESH OIL 

SPRINC SHACKLE. FILL OIL RESERVOIR' 

WITH ENGINE OIL 

CLUTCH THROWOUT AND PEDAL OIL! 

WITH ENGINE Oil. 

'STEERING CONNECTING TUBE, SCREW 

.DOWN CUP UNTIL GREASE OOZES OUT 

JJfSTEERING GEAR. PACK CASE WITH 
"[""([GREASE 

STEERING COLUMN. REMOVE PLUG 
TOP AND OIL WITH ENGINE 01 
'BATTERY. ADD PURE WATER TO BRINI 
.ELECTROLYTE 1" ABOVE PLATES 
[TRANSMISSION. FILL WITH TRANS. OIL! 
[TO HEIGHT OF TOP OF FILLER TUBE 

[GEAR SHIFT RODS AND YOKES' 1 3) 
WITH ENGINE OIL 

(BRAKE ROD LINKAGE. SIX PLACES. 01 
[WITH ENGINE OIL 

[BRAKE ROD LINKACL SEVEN PLACES: 
OIL WITH ENGINE OIL 



I) -I 1 



UNIVERSAL JOINT. FILL CASE TWO- 
THIRDS FULL WITH TRANSMISSION OIL 
BRAKE SHAFTS. FOUR PLACES. SCREW1 
t DOWN CUPS UNTIL GREASE OOZES OUTJ~ 

{SPRING CLIPS. KEEP THEM TIGHT 

REAR WHEEL PACK ROLLER BEARINGS)^-^ 
WITH CUP GREASE ] 

WHEEL CLEAN OUT OLD GREASE AND)/ 
WASH WITH KEROSENE. PACK WITHK 
FRESH CUP GREASE 



I I 



SPRAG. OIL JOINTS WITH ENGINE OIL 

SPRING LEAVES. SEPARATE LEAVES' 
AND SPREAD WITH GRAPHITE AND 01. 

SPRING SHACKLE. FILL 01 RESERVOIR! 
WITH ENGINE OIL 



/oOOO MILES E 
/ 1000 MILES ~D 




500 MILES C 



/ 250 MILE S B 
DAILY 



STARTING CRANK. TWO GREASE CUPS.) 
SCREW DOWN UNTIL GREASE OOZES OUT 

[RADIATOR. FILL NEARLY TO TOP WITH 

VT.CLEAN WATER 

\[COOLING SYSTEM. DRAIN, FLUSH 0UT1. 
ISEDIMENT, AND FILL WITH CLEAN WATER 

SPRING BOLT. FILL 01 RESERVOIR 
WITH ENGINE OIL 

FAN. REMOVE PLUG IN HUB AND OIL 
WITH ENGINE OIL 

FAN. CLEAN OUT OLD GREASE AND' 
.PACK HUB WITH FRESH GREASE 
YMWHEEL. REMOVE CAP AND OUTER BEAR. 
\ IMG. PACK HUB WITH GREASE 
WHEEL. CLEAN OUT AND WASH HUB' 
AND BEARINGS WITH KEROSENE. PACK 
\ \ [WITH FRESH GREASE 

STEERING KNUCKLE. FILL OIL RESER. 

VOIR WITH ENGINE 01 

STEERING CROSS ROD. FIL 01 CUT 

WITH ENGINE 01 

GENERATOR. TWO 01ERS. TWO DROPS! 

OF ENGINE OIL IN EACH 

THROTTLE LINKAGE EIGHT PUCES. 
OIL WITH ENGINE OIL 

SPRING LEAVES. SEPARATE LEAVES AND 
SPREAD WITH GRAPHITE AND OIL 

SPRING SHACKLE FILL OIL RESERVOIR 

WITH ENGINE OIL 

CAS TANK SEDIMENT TRAP. OPEN DRAIN 

FOR A FEW SECONDS 

CLUTCH BEARINGS. FILL OIL CUPWITH1 

ENGINE OIL GIVE GREASE CUP 3 TURNSJ 

GEAR SHIFT AND BRAKE LEVER. OIL] 
WITH ENGINE OIL 

UNIVERSAL JOINTS. FILL CASES TWO- 
THIRDS FULL WITH TRANSMISSION OIL 
TRANSMISSION. DRAIN AND WASH OUT 
WITH KEROSENE. FILL WITH FRESH 
TRANSMISSION OIL 

SPRAG RELEASE ROD. 01 WITH ENGINE 
OIL 

UNIVERSAL AND SUP JOINT. FILL TWO-' 
THIRDS FULL WITH TRANSMISSION OIL j 
SPRAG RELEASE ROD. OIL WITH ENGINE] 
OIL 

1INGB0LT. FILL OIL RESERVOIR WITI 
ENGINE OIL 

BRAKE ROD LINKAGE TEN PUCES. 01 
WITH ENGINE OIL 

AKE SHAFTS. FOUR GREASE CUPS. 
SCREW DOWN UNTIL GREASE OOZES OUT. 

PRINC CLIPS. KEEP THEM TIGHT ]|A 
JREAR WHEEL PACK ROLLER BEARINGS 
^-OWiTH CUP GREASE 

\ [WHEEL CLEAN OUT OLD GREASE AND 
NWASH WITH KEROSENE PACK WITH 
[FRESH CUP GREASE 
REAR AXLE. FILL WITH TRANSMISSION 
OIL TO HEIGHT OF TOP OF FILING PIPE 
REAR AXLt DRAIN AND WASH OUT 
WITH KEROSENE FILL WITH FRESH 
TRANSMISSION OIL 

SPRING LEAVES. SEPARATE LEAVES AND 
SPREAD WITH GRAPHITE AND OIL 
—-JSPRING SHACKLE. FILL OIL RESERVOIR 
[WITH ENGINE OIL 



1- 



I" 



Inspection — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
INSPECTION SECTION 

LECTURE II 

Repair System, A. E. F. 

In order that you may have a bird's-eye view of the repair system as oper- 
ated in France, I will outline to you the repair system showing the different 
parks and establishments, which start with the company near the Front line 
and end up with the Reconstruction Park, which is the factory for the A. E. F. 

Attached to each company is a light repair truck on which is a standard 
stock of tools and parts, made up of ten days' supply of spark plugs, nuts, 
bolts, valve springs, brake lining and the minor parts needed in quick repairs; 
also a fairly complete assortment of hand tools. That stock is kept up by 
requisition every other day on the next larger unit, which is the Service Park. 
The stock on hand, plus the requisitions going through channels, should equal 
the standard unit equipment list of that truck at all times, and the company 
mechanic should never allow that equipment list to get down. 

The next step in the chain is the Service Park. A Service Park is a mobile 
machine shop unit with a personnel of 35 men and an officer. This personnel 
is made up of the different trades. There is a radiator man, chassis man, en- 
gine man, electrical man, tire man, and so on. The Service Park keeps on 
hand at all times a ten day supply of larger parts (not assemblies) such as 
connecting rods, bearings, bushings, brake lining, etc. A Service Park is 
supposed to take care of the repairs on 148 trucks, and a proportionate num- 
ber of passenger cars and motorcycles, and can handle repairs on six trucks 
at one time in the park. The unit equipment list for a Service Park is laid 
down in bulletins and consists of a definite number of bearings, connecting 
rods, bushings and parts for all the vehicles which it serves. No repairs are 
attempted in a Service Park that will require more than ten days to complete. 

The next link in the chain is the Overhaul Park. The Overhaul Park is a 
much larger unit and may consist of any number of men. We have a system 
of repair sections, groups and units. The section is the smallest and consists 
of 77 men and 3 officers. By grouping together 4 sections and a headquarters 
we make a repair group. By grouping together 4 groups and a headquarters 
we have a repair unit. We can make an Overhaul Park of any size we want. 
We can take one section of 77 men and 3 officers and make that an Overhaul 
Park, or take 4 sections and call it a Repair Group and make that a larger 
Overhaul Park or take 4 groups and make it our largest unit, which is the 
Repair Unit, and consists of 1280 men. 

The repairs done in the Overhaul Park are practically all repairs that can be 
made to the vehicle except reconstruction. If a vehicle is badly damaged by 
shell-fire or totally wrecked through misuse so that all the working parts will 
have to be replaced and it is more a question of salvage than repair, that 
vehicle goes back to the Reconstruction Park and is not touched by the Over- 

CMC 



Inspection — Lecture II Page 2 

haul Park at all; but, if the work consists of tearing down the motor and re- 
building, tearing out transmissions, rear axles, etc., the Overhaul Park han- 
dles it. Assemblies are taken apart here and assemblies are carried in stock 
as part of their standard list of parts and supplies for the trucks which they 
are supposed to serve. Each Overhaul Park can take care of the repairs on 
1800 or 1900 trucks. It can handle 100 trucks at one time in the park. The 
Overhaul Park is, of course, farther back from the line than the Service Park. 
The Service Park is usually within sound of the guns and near the rail head ; 
within reach of the supply and ammunition trains. The Overhaul Park would 
probably be back 25 to 30 miles from the line and may be more, depending 
on whether that sector of the Front happened to be active or not active. 

Overhaul Parks have quite an elaborate machine tool equipment and can 
actually make small parts. The time factor enters into all repair work ex- 
cept that done in the Reconstruction Park. No repairs are allowed in a Serv- 
ice Park that require over ten days. If a vehicle in the opinion of the in- 
spector will require over ten days for its repair, it is sent back to the Overhaul 
Park. If it requires more than 20 days in the Overhaul Park it is sent back 
to the Reconstruction Park. In that way we do not clog up the Service and 
Overhaul Parks with a lot of dead material, thereby making it immobile. 
Mobility must be the first consideration. I might add that an Overhaul Park 
quite often is an Advance Spare Parts Depot and by an Advance Spare Parts 
Depot I mean a depot that keeps 30 days' supply of all parts for all trucks 
operating in the area in which it serves. That includes rear axles, assemblies, 
transmission assemblies, clutch assemblies, even motor assemblies, and, where 
it is deemed advisable, a motor is set in and the old motor taken out, repaired 
later and put back in stock. In fact, repairs of this kind are frequently han- 
dled this way; replace assemblies and put the truck into commission, repair 
the taken out assembly at another time when work will permit. 

The next link in the chain is the Reconstruction Park, which is a very large 
organization. It has a large roofed area and you might liken it to one of our 
big automobile or truck manufacturer's plants in this country. It is an enor- 
mous proposition and when I tell you that for one army alone we have to have 
upwards of 80,000 vehicles in France you can realize that we must have a 
large factory to look after their repair. 

At the Reconstruction Park all reclamation work is taken care of. We call 
it salvage. All complete overhauls are made there ; vehicles come back from 
all the Overhaul Parks to the Reconstruction Park when the time factor will 
not allow the Overhaul Park to make the repairs. Broken parts and broken 
vehicles have to be returned by every member of the A. E. F. for salvage. 
Even though you think a part is absolutely valueless you are charged with the 
responsibility of seeing that that part goes back for salvage. The metal in 
broken parts can be melted up and reshaped into tools; babbitt can be melted 
and re-used ; broken parts can be repaired by careful machine work and by 
brazing and welding. We also must have broken and worn out parts returned 
in order to know whether those parts are defective from poor workmanship or 
material, or worn out through fair wear and tear. This is important, for we 
must make recommendations for changes in construction on the basis of this 
information. Broken parts come back through the various parks and estab- 
lishments to the Base Spare Parts Depot which is in close proximity to the 
Reconstruction Park. The Base Spare Parts Depot turns the broken parts 
and supplies over to the Reconstruction Park which reclaims all parts that it 
it possible to reclaim and then turns them back to the Base Spare Parts Depot 
for stock. That is the work of the Reconstruction Park. In other words, 

CMC 



Inspection — Lecture II Page 3 

when you order parts from the Service Park you may not get a new part but 
you may get a part that has been rebuilt. It is just as good. That system of 
salvage and the importance of it I will not dwell further on this morning, but 
Will make it the subject of a separate lecture later on in the course. 

I will now go back to the company repairs. Company repairs are quite 
the most important factor in the Motor Transport Service of the A. E. F. If 
the proper care is not given to lubrication and adjustment and repair work in 
the company, both in park and on the road it echelons all the way down the 
line, our Service Parks are overcrowded, our Overhaul Park is overcrowded 
and our Reconstruction Park is swamped. And really, when you come down 
to the last analysis there is very little excuse for a vehicle going back from 
the company to the Service Park except for periodical overhaul and except 
for damage from shell-fire. If the driver is a good driver, properly trained, 
if the company mechanic is an iron roaster as far as upkeep is concerned and 
is on the job, there will be a minimum of extensive repairs and consequently 
less work for the Service, Overhaul and Reconstruction Parks. Company re- 
pairs occupy the full time of the Company Mechanic and his assistants and a 
large share of each and every driver's time when not actually at the wheel of 
his truck. 

Company repairs consist of keeping nuts and bolts tight, cleaning spark 
plugs, trimming solid tires, making minor adjustments to electrical, oiling 
and cooling systems, cleaning crank case, changing oil and cooling systems, 
and greasing transmission and differential at proper time. In addition, com- 
pany mechanics and drivers must report at once parts that show undue wear, 
breakages and suspected trouble. Where the repairs are beyond the facilities 
of the company mechanic, and the light repair truck the Company Commander 
should arrange at once that this truck be sent back to the Service Park with 
all speed. No extensive repairs are undertaken in the company such as tear- 
ing down the motor or any of the other assemblies such as transmission, rear 
axle, etc. In the first place the company mechanic has not the equipment to 
do this work and in the second place it would require too much of his time 
and mean that he would have to neglect minor adjustments and upkeep work 
on the rest of the trucks, all of which is important. 

We will take up the next responsibility of the drivers. There seems to 
nave been a great deal of discussion and some misunderstanding as to how far 
the driver should be educated in the mechanical construction of his vehicle. 
Some have said that he should not have any instruction except in driving 
and that he should be entirely ignorant of the theory and practice of Auto- 
mobile Engineering. That has not been our experience. On the contrary, 
we have tried to give the driver every bit of instruction along that line that 
the time afforded while he was going through school, and if he were there for 
quite a length of time he kept delving further into the construction and ad- 
justment of the vehicle which he was operating, both the theoretical and the 
practical, so that when he was through with his training he knew when shift- 
ing into first gear, just what was happening in the transmission, and he also 
knew the difference between a surge in the motor caused by the carburetor 
being badly adjusted, and a surge due to two cylinders not firing properly. 
A driver is very often called upon to make minor adjustments himself, under 
the supervision, if possible, of a company mechanic, but the company mechanic 
cannot be everywhere at once and the driver has to be able to do these things. 
The driver is responsible for the proper cleaning of his vehicle. Perhaps that 
does not sound important to you, but it is highly important. We have suffered 
a great deal of criticism in France in the American Army by the appearance 

CMC 



Inspection — Lecture II Page 4 

of our trucks. They were not washed, and mud would remain on them for 
weeks; they were not properly lubricated. Drivers were sloppy in appearance 
and driving, and very often they would pull up at some Divisional Headquar- 
ters alongside a British or a French Headquarters Staff Car. The comparisor 
was terrible to look upon. The British or French cars would be as bright as 
a new penny, although in service perhaps for three or four years. Every bit 
of brass and metal was shined up, the frame, the drive shaft and rear axle 
housing, ordinarily neglected by you and me, were thoroughly cleaned up. 
You could put your hand on any part of the car. That is why those vehicle 
are running after four years of service. The cleaning of the vehicles should 
be done every day. There is one part of the cleaning that can be done every 
day and must be insisted upon by every Company Commander, noncommis- 
sioned officer and mechanic, and that is that the dirt and flinty rock in the 
dust be cleaned from the spring shackles and all the moving parts of the 
vehicle. That is absolutely essential, because, if I could go into the spare 
parts end of it with you, and the troubles we have had, and the troubles we 
will always have in keeping spare parts in France it would very nearly bring 
tears to your eyes. We have not had anywhere near a sufficient stock of 
spare parts for any of the vehicles in France up to the first of May this year 
The lack of spare parts is a very serious proposition in France. The prope» 
cleaning of the car will cut down the demand for spart parts tremendously. 

The next thing is the lubrication of the car. There are certain things which 
must be done every day, certain things which must be done at stated intervals, 
such as every 250, 500, 1000 and 2000 miles. You must know the M. T. C. 
Manual backwards and studv up on those things which are to be done at the 
various periods. 

In addition to lubrication, there are other things which must be done at 
the stated intervals before mentioned. I will enumei-ate them to you and you 
will find all of these rules in the Manual beginning on page 69. 

(a) Care must be given to appearance, as well as to the mechanical per- 
fection. See that the body and wheels are cleaned of dirt, and inside of body 
cleaned out. 

(b) Be on the lookout at all times for all leaks, and for unusual noises; 
find the cause immediately and remedy it. 

(c) In screwing up grease cups always make sure that the grease has 
actually been forced into the bearing. 

(d) Never cut out the muffler. 

(e) Never, under any circumstances, fill the gasoline tank or work on 
the carburetor in the presence of a naked flame or an oil lantern. If this work 
must be done in the dark, use an electric torch. 

204. After each run. (To be done as soon as truck returns from run.) 

(a) Fill up gasoline tanks (including reserve supply) oil lanterns, head- 
lights and generators. 

(b) Drain carburetors. (Much water and other impurities are often 
found in gasoline.) In freezing weather drain radiators. 

(c) Remove mud and dirt from places in immediate proximity to joints 
and moving parts, such as reach rod joints, spring shackles, distance rod 
hangers or joints, torsion rod joints and springs. 

(d) After removing dirt turn down grease cups at all places one turn. 

(e) Examine and tighten all loose nuts, screws, etc., including those of 
the wood-work. 

CMC 



Inspection — Lecture II Page 5 

(f) Wash entire truck, if possible. 

205. At end of 250 miles: 

(a) Fill up oil grease cups and see that oil holes are not stopped up. 

(b) Clean motor and pan under motor; clean spark plug; oil magneto 
(only drop or two) ; clean carburetor. 

(c) Examine clutch; permit no oil on a leather faced clutch. 

(d) Transmission Case : Fill with lubricant if necessary. 

(e) Brakes: Examine and regulate tension. 

(f) Chains: Examine tension. 

(g) Clean oil strainers. 

(h) Examine all wiring as to insulation and connections, 
(i) Go over all nuts and bolts. 

206. At end of 1000 miles: 

(a) Drain crank case, wash with kerosene, and fill with fresh oil. (Save 
old oil to return to service park.) 

(b) Jack up body and clean and grease spring leaves. 

(c) Remove chains, bathe in kerosene, clean with brush, grease and put 
back. 

(d) Fill differential with oil. 

(e) Examine all grease boots and clean and refill if necessary. 

I want to caution all of you to be constantly looking for loose nuts and con- 
nections and be constantly tightening these things. Our spare parts situation 
in France will always be a serious one. We will never have as many parts as 
we need and you will seldom have the supplies and parts when you need them. 
For this reason, whenever your truck stops to load or unload, or whenever you 
arrive in the park and have a few minutes, go over your truck very carefully 
from the front bumper through to the tailgate ana see that everything is tight 
and that no defects or mechanical troubles are liable to hold you up on the 
road. The Motor Transport Service in France is charged with moving the 
freight of the A. E. F. We cannot move freight if your truck is out of com- 
mission. Troubles corrected before they become serious prevent excessive 
demands for spare parts, decrease the work of the company mechanics of the 
Service Park, of the Overhaul Park and of the Reconstruction Park and 
greatly simplify the maintenance problem. A burnt out or frozen bearing is 
inexcusable and in France is cause for court-martial proceedings in every case. 
You will not be able to give any reason whatsoever for trouble of that nature. 
There is no excuse and none will be accepted. I have been an Inspector of 
Motor Transportation for several months back in France. I know whereof I 
speak and I know that the causes of break-downs in the Motor Transport 
Service were in 7 cases out of 10 due to the inefficiency of the drivers of 
vehicles. These drivers were not properly trained. They had no conception of 
discipline before going to France. They were slovenly in their personal ap- 
pearance. Their trucks were dirty, not properly lubricated, parts were lost 
off the trucks, thereby tying up that place of equipment for days and some- 
times weeks; bearings were burned out, brakes burned out, clutch facings 
ripped off unnecessarily, radiators smashed, and the vehicles generally not 
able to handle the freight. The things I have mentioned here if allowed to 
continue, are nothing short of criminal offenses which at this time deserve the 
strictest disciplinary action. Both the driver and the company mechanic are 
responsible for the log-book which accompanies every vehicle in France. This 

CMC 



Inspection — Lecture II Page 6 

book is issued to the vehicle at the Reception Park at the Port of Debarkation. 
It stays with the vehicle as long as the vehicle is in service. This log-book is 
about 4 inches wide and 6 inches long. In it are kept records of transfers 
of the vehicle and of all repairs made by any repair park. The first page of 
the book is given over to the specifications of the truck, the engine number, 
the chassis number, U. S. number, the type and model of the truck and the 
detailed list of the equipment which was placed on the truck at the Reception 
Park. Beginning with the next page there are spaces for the driver to sign 
for the vehicle and for its equipment and in each case of transfer his signa- 
ture is witnessed by the signature of the Commanding Officer. The last 3 or 
4 pages of the book are given over to records of repairs made. This record 
shows the number or name of the repair park making the repairs, what the 
repairs consisted of, what spare parts and supplies were required to make the 
repairs, and the signature of the inspector or officer entering this data. The 
information regarding repairs which is entered in this book is invaluable to 
us at Headquarters as it shows the performance of a truck and also shows the 
class of repairs that are having to be made on that particular make of vehicles 
and enables steps to be taken for the correction of defects and changes in 
construction. This logbook is to the car what the Service Record is to the 
soldier, and the driver is held rigidly responsible that it is not lost and that 
it is kept clean and all data entered up to date. 

The driver's further responsibility is the proper loading and lashing of his 
cargo. It is very important that his truck is not overloaded and that his 
cargo is so placed that he will get traction, which in certain kinds of weather 
should be over the rear wheels, and he should watch that loading and unload- 
ing carefully. He does not do it himself but he is charged with the responsi- 
bility that it is put on properly and that he gets a full load. Every vehicle in 
France must carry a full load every time it turns a wheel. We must insist 
on full loads as far as possible, due to the scarcity of equipment. 

The company mechanic is also responsible for the tool equipment on the 
light repair truck which is part of the company equipment. He signs for 
these tools from the Company Commander; he signs for all spare parts and 
motor supplies issued to the company, and he issues all these things out to the 
assistant mechanics or drivers on memorandum receipts so that he has his 
records clear and in order at all times; and as I said before, the company me- 
chanic is charged with the responsibility of keeping up the unit equipment 
list of the repair truck and the cargo trucks; this is done by requisition on the 
Service Park for tools that have been broken or worn out and for supplies 
that have been issued from the light repair truck. There is a unit equipment 
list for every type of vehicle that is operated in France. This unit equipment 
list includes all the necessary tools and a few small parts and supplies which 
should be carried with the vehicle at all times. Whenever tools are lost, 
broken or worn out the driver must immediately notify his Commanding Offi- 
cer and arrange for the replacement of these articles without delay. As far 
as possible, such articles are replaced from the stock kept in the light repair 
truck. Everything about the truck that can be taken off or removed in any 
way is entered on this unit equipment list. The drivers are particularly re- 
sponsible for everything appearing on the list. 

The proper handling of a vehicle on the road will save a large amount of 
repair work in the company and will save spare parts, the value of which can- 
not be estimated in France. I want everyone of you to consider this fact 
when driving. Conserve your brake lining by intelligent use of the brakes. 
If you have a long hill to go down, thi-ow your car into first or second gear 

CMC 



Inspection — Lecture II Page 1 



and only use your brake to bring the car to a dead stop on the hill. When it 
is necessary to make an emergency stop with the brakes, do not hold the brake 
on until it gets heated up and burns out the lining. When you get into a hole 
or a bad place and are stuck, be careful not to rip the facing off your clutch 
or strip your rear axle pinion. Never allow your truck to be over-loaded. If 
approaching a bump or hill in the road, slow down in order not to run the 
risk of breaking a spring. Never attempt to back your truck unless you have 
some one walking back of it or standing in front of the truck to show you 
which way to go and how to avoid smash ups and accidents. 

These are only a few things that you should watch and before you have 
finished your course we will attempt to warn you of as many other things 
as time will permit. Whenever your truck is standing idle on the road for 
loading or unloading, get out your oil can and monkey wrench and go over 
your truck carefully. If you do this you will catch troubles before they be- 
come serious and you will have to spend less time on your truck in the park 
and consequently have more time off to take care of your personal needs and 
for pleasure. 

Conservation of everything shipped overseas for our troops is our watch- 
word in France and I want you to get into the spirit of conservation before 
going over so that it will become natural to you when you arrive. 

One very important factor which will contribute enormously to the success 
of your organization is team work. I mean by team work, hearty co-operation 
between every member of the organization — a spirit of wanting to help each 
other, a spirit of pride in your organization, a serious viewpoint on the im- 
portant work that you are doing. Be very jealous of the reputation of your 
company. Uphold its honor, protect its good name and at all times reflect 
credit upon it whether in camp or on the road or on leave. We call this 
teamwork. "Esprit de Corps," in France, and you will hear a lot about it 
when you get "Over There." In order to make Esprit de Corps worth while to 
you, if such a thing be necessary, a system of rewards for efficiency and good 
service has been worked out whereby a driver who always has his vehicle 
ready to roll, who never has any criticism of the operation of his vehicle or 
of his personal appearance and conduct, receives time off, in addition to the 
regular company liberty, on certain stated days of the week. If his record 
is clean for a period of four weeks, a white star about 3 inches in diameter is 
stencilled on the side of his car underneath the driver's seat. This white star 
means that the driver has a record of excellence for a period of at least 4 
weeks, and it is known throughout the A.E.F. to have that meaning. You 
cannot earn that white star nor the time off, which I have mentioned before, 
if you are ignorant of what is expected of you and do not know how to keep 
your truck up, how to keep it clean and properly lubricated, etc. Therefore, 
it is up to you to learn these things so thoroughly that within the first two 
months after arrival in France you will have a white star on the side of 
your car. 

We will now cover the responsibilities of a driver: first, to himself; second, 
to his Company Commander; third, to his truck; fourth, to the Service as a 
whole. All the points that I will cover will be the result of practical experi- 
ence in service in France and for your own good and well worth remembering. 

First of all, the driver's responsibility to himself. In France you are sub- 
jected to a great many temptations and you owe it to yourself and to the 
Service and to your family to keep your physical being clean at all times. 
General Orders will be read to you when you arrive in France covering this 
point, and you will be carefully instructed along the lines of personal appear- 

C M c 



Inspection — Lecture II Page 8 

ance. You owe it to yourself to have your personal appearance, your clothes 
and your shoes always above reproach. There is nothing that reflects more 
credit on the A.E.F. than the personal appearance of its soldiers. England 
and France have devoted a great deal of attention to that point and America 
not enough. The result is that I have been heartily ashamed oftentimes when 
American drivers and either French or British have come together. The com- 
parison was anything but flattering to the Americans. 

Another point of responsibility to yourself is the spirit with which you enter 
into your work, the pride you have in your organization, and the personal 
pride regarding your own discipline in camp or on the road or on leave. Do 
not take the matter of saluting and of respect for superior authority as an 
odious job which must be gone through with in order to avoid punishment. 
When you salute an officer you salute the insignia which he carries on his 
collar and his shoulders. That insignia means the Flag. It means the Presi- 
dent of the United States. Its real meaning, if spoken by word of mouth 
would be: "I respect the responsibilities which the President has delegated to 
you. I honor my Flag and my Country and I am ready to carry out your 
commands." When the officer returns the salute its meaning is: "I know 
your loyalty and I shall try to lead you to the best of my ability." Never 
allow yourself to be lax in the matter of saluting. In fact, in France this 
matter of saluting is of paramount importance. The closer you get to the 
line or to the Front, the more rigidly this regulation is enforced. 

Your responsibilities to your Company Commander are as follows: You 
must be absolutely obedient to his orders. Accept them without question or 
delay. Your Company Commander has additional information about certain 
movements of troops, certain contemplated changes of location of batteries, 
the condition of roads, and other things which are unnecessary to advise you 
of and which for military reasons cannot be published. For this reason when 
given an order to arrive at a certain point at a definite time, let nothing under 
heaven interfere with your being there. A tremendous lot may depend on 
your truck being on time and being at a certain point without any question 
of doubt or peradventure. When given an order to go to a certain dump, to 
transport certain definite quantities of supplies, never leave that dump with- 
out the required number of fuses, shells, etc., that are noted on the order. 
Shells are no good without fuses, and fuses are no good without shells. The 
same applies to subsistence stores which are hauled from Quartermaster 
dumps. You do not want the boys in the line who are doing the fighting and 
risking their lives every second of the day and night, to be short anything of 
any nature that will help them to win out. I want you to feel that responsi- 
bility. Your Commanding Officer will be very severely criticized in case you 
do not carry out his instructions to the last detail and you do not want your 
CO. and your entire organization to suffer because of your laziness or care- 
lessness. 

Another responsibility to your Company Commander is absolute loyalty. 
Even if your CO. is not all that you would wish him to be, be loyal and up- 
hold his reputation to the best of your ability. He represents your company 
and unless his record is clean in the eyes of other organizations and other 
people, your company record will suffer accordingly. Whenever your CO. 
passes or enters the room where you are resting never fail to salute. Respect 
his authority, respect his responsibility, and be always on guard to protect 
his and your company's reputation. 

The driver's responsibilities to his truck and equipment are numerous. You 
are entrusted with a good many thousands of dollars worth of Government 

CMC 



Inspection — Lecture II Page 9 



property. This equipment at times has a value which cannot be estimated 
for several reasons. First of all, due to the lack of ships' tonnage and the 
activities of the submarine, it is extremely difficult, and up to the present time 
impossible, to get enough equipment to France to move the freight. Every 
vehicle must do the maximum amount of work of which it is capable in order 
to render the service with which the M.T.C. is charged. At times, for strat- 
egical and tactical reasons, your truck may be the means of turning the tide 
in favor of our boys in the lines and at those times your truck off by itself 
or in company with a few others, is beyond estimation of value. One truck 
driver at Chateau Thierry practically saved the day for our Marines by bring- 
up machine gun ammunition at the psychological moment under terrible fire, 
and delivering it in full sight of the Germans and in the face of their fire. 

Whenever you take over a truck in France you sign for the truck and its 
equipment. By this equipment I mean the tools, the small parts and supplies. 
The tarpaulin and bows, the lamps, fire extinguishers, towline, pick and shovel, 
and all other equipment which you will find on the unit equipment list for a 
truck. This unit equipment list is standard and is made out in duplicate at 
the time the truck is put into service. The original is printed on card board 
and is to be kept in the truck at all times. You are responsible for the items 
checked or marked on this card board and if, when you turn the truck over 
to another driver, anything is lost or stolen, you must pay for it. No excuses 
are accepted and none should be given. This is made necessary for several 
reasons, but the main reason is that equipment is too scarce and too valuable 
and too difficult to replace in France. When you use an extra spark plug 
from your tool kit, go immediately to the company mechanic and requisition 
for a new one. When you use cotter pins, nuts and bolts, or the valve spring 
or valve from your truck equipment, immediately get the same supplies from 
the company mechanic to replace them. Never allow your equipment to get 
down under any circumstances. These supplies and these tools that appear 
on the list are the minimum amounts which are necessary to keep your truck 
in service. Therefore, you do not want to be caught short of any of these 
things when emergencies arise on the road away from your company park 
or a repair park. 

For the same reason that you must keep your pei'sonal appearance what it 
should be, and for other reasons which I will enumerate to you, you must 
always have your truck or car or motorcycle spotless and in adjustment. 
When I say spotless I mean just what the word implies. You will see British 
and French equipment when you arrive in France, and that sight will be an 
incentive for you to keep your vehicle clean at all times. When a vehicle is 
properly cleaned and lubricated there will be a minimum demand for spare 
parts and supplies. These supplies are very difficult to get in France and we 
will never have as many as we need. The proper way to clean your truck 
will be shown to you during this course. You will be shown how to clean 
your engine, what parts, such as spark plugs, porcelains, wire terminals, etc., 
should be guarded against breakage. You will be shown what parts should 
be cleaned with a brush and what with a cloth or with waste. The same applies 
to other parts of your vehicle throughout the chassis. You will not have gaso- 
line or kerosene to get this grease and dirt off quickly, but you will be pro- 
vided with a solution of sal soda and water which will cut the grease and do 
just as good a job as kerosene or gasoline which are such valuable supplies to 
us. When you have your engine thoroughly cleaned, including the pan under- 
neath, start in on your traiismission case, the short shaft between the trans- 
mission and the clutch, and the pan and the frame around these assemblies, 

CMC 






Inspection — Lecture II Page 10 

then go to the rear axle. Clean the housing, the brake mechanism, the pro- 
peller shaft and universals, the torque rods and connections, the brake equal- 
izer and connections, and do not shirk a single thing. Then wash the body 
and chassis of your truck thoroughly. When the entire vehicle has been 
cleaned, go over it carefully with an oil can and lubricate all the connections 
not supplied with grease cups, turn all grease cups down one turn, and if 
there is any question of whether the grease is getting to the bearings when 
the cup is turned, turn the cup down as far as it will go, and if necessary, 
fill it up again and turn it down a second time until the grease actually 
shows up around the joints or bearings. Make sure that the part is being 
lubricated. More parts and supplies are needed for motor vehicles be- 
cause of lack of lubrication than for any other cause. Test the oil in your 
crank case, in your transmission, in your differential. See that you always 
have the proper grade and kind of oil for the assemblies. Take off your 
wheels periodically, at least once a week, and see that the bearings are prop- 
erly lubricated and adjusted. Outside of driving, your main duties while in 
camp or during delays on the road at loading and unloading points are to 
clean and lubricate your vehicle. This is one of the most important points 
that I can touch on during this course, and I want you to give it the attention 
which I know it deserves and which will be required of you in service in 
France. 

In the matter of adjustments which you will be called upon to make and 
which is another responsibility which you have to your truck, a definite list 
of these which will be taught the drivers will be furnished to your instructors. 
There has been not a little discussion in the United States as to the amount 
of actual mechanical work which a driver will be called upon to do, or rather 
that which a driver should know and be instructed in at M.T.C. Schools. You 
will be thrown on your own resources very often where it will be necessary 
to make minor adjustments to your fan belt, your carburetor, your electric 
system, your clutch, your wheels, steering gear and your engine. Ordinarily, 
in your company park you are charged with reporting to the company me- 
chanic parts that are out of adjustment or broken or in need of repair. He 
either directs you to make the adjustment, at the same time instructing you 
how to do it, or he details one of the assistant mechanics to do it for you. All 
repairs and adjustments in park and on the road are absolutely under the 
direction and supervision of the company mechanic. If he is not present on 
the road when you are traveling alone or in a small convoy, you must make 
emergency repairs and adjustments. Therefore, get all you can from the lec- 
tures and practical work during the course, as to the construction of your 
vehicle and the adjustment of its different parts. Most important of all is 
the tightening of loose connections, nuts and bolts before they cause further 
serious trouble. You must always be on the watch for such trouble. Learn 
to use your monkey wrench or spanner or screw driver, but there is a lot to 
be learned on that point. For instance, if a monkey wrench is not tightened 
up, when you attempt to turn a nut the wrench will slip and probably skin 
your knuckles, but worst of all, will so mutilate the nut that no kind of a 
wrench will tighten it. Always have your wrench adjusted properly and do 
not attempt to pull the nut so tight that you will strip the threads or break 
off the bolt. This is very easily done unless you are careful. If you have not 
the proper size open end wrench with which to do the work, take a larger 
spanner than the one required, insert a washer or a piece of steel between the 
nut and the jaw of the wrench and you have a tool that will do the job. 
These are only two instances to show you that there is such a thing as intelli- 
gent use of tools, and you will be called upon oftentimes, due to shortage in 

CMC 



Inspection — Lecture II Page 11 

your equipment, to be resourceful in the use of what you have. At least once 
a day in the park go over every nut and bolt and connection on your truck 
to see that everything is in shape. Have a rag or a piece of waste under your 
seat with which you can wipe off the engine and chassis and body. If you do 
this you will catch troubles that might develop in the next mile that you travel, 
and in addition you will have less work to do when you get back to the park. 
Should the truck be put out of commission through your fault, you are tying 
up equipment which, as I told you before, is invaluable. Of course, if your 
truck is struck by shell fire or is called into the service park for periodical 
overhaul, that is not your fault. Those are the only two times, however, when 
it can be out of service without reflecting discredit on you. 

There are all sorts of punishments possible and every one is used for men 
who do not keep up their equipment and who are lax about their discipline 
and personal appearance. Those punishments vary from K.P. work and extra 
duty to loss of pay and even general court-martial proceedings. As is only 
right, there are, on the contrary, rewards for those who behave themselves 
and are careful of the equipment entrusted to them. One system of rewards 
has been worked out and is in operation in France and consists of extra time 
off outside of the routine company liberty, and in promotion to higher grades, 
I will tell you of this plan of rewards in my next lecture. 

The driver's responsibility to the Service as a whole is very great and far 
reaching. In the present war, motor transport occupies a very prominent 
place. The German Army, due to the lack of gasoline and rubber for tires, 
and due to the fact that it has been educated to the use of railroads and horse- 
drawn vehicles, transports nearly all of its supplies by light narrow-gauge rail- 
road, right up to the line. It uses a minimum amount of motor transport. 
On the other hand, all of the Allied Armies, and particularly the French and 
American Armies rely almost entirely on motor transportation. Supplies are 
brought up to what is called the rail-head from the supply depots far in the 
rear. The rail-head is usually 8 to 15 miles from the front line, by motor 
transport. From distributing point to the regimental kitchens, supplies are 
carried by animal drawn transport. It very often happens, though, that trucks 
must deliver supplies direct to the regimental dumps which are immediately 
back of the line and farther forward than the distributing point. That im- 
portant gap which is filled by motor transport from the rail-heal to the dis- 
tributing point is the area in which you will operate in France. You can 
plainly see your great responsibility to the Service as a whole, which is to 
move the freight and deliver the supplies, oftentimes under shell fire, over 
roads that are crowded with guns, troops, vehicles of all description, in sun- 
shine and rain, night and day, to the boys in line. The better service you 
render to the Army and to your Country, just that much quicker will we be 
back in our homes away from all this ghastly business, and the quicker you 
will bring about a successful issue for your own and the Allied Armies. You 
must have unlimited pride in the fact that you are an American soldier. Your 
personal appearance and deportment, if correct, will prove the greatest ad- 
vertising factor which this country could put out to the Allied Armies. This 
is a mighty serious business that we are engaged in and only when you are 
on leave can you sit down and think of lighter things, but even then you must 
carefully protect the good name of the United States and the Flag. 

We will now speak of first the class of repairs and adjustments that you 
as a driver must be conversant with, and secondly the details of your respon- 
sibility and accountability for equipment placed in your charge. 

CMC 



Inspection — Lecture II Page 12 

There are three things about a motor car or a motor vehicle which require 
constant looking after in France. They are all of equal importance and it is 
hard to say that one should have more emphasis than the other. You should 
know how to drain your carburetor and clean out the dirt which is sure to 
collect. Gasoline as it arrives in France is of very poor quality. It contains 
impurities such as water and dirt and tests very low for specific gravity. This 
water and dirt must be kept out of the float chamber away from the needle 
valve. If there is no pet cock drain plug on the bottom of the carburetor, it 
will be found necessary to disconnect the feed pipe at the carburetor and allow 
both the pipe and the carburetor to drain. Water also accumulates in the 
bottom of the tank. However, by allowing the gasoline to run out of the 
feed pipe, when disconnected at the carburetor, into a pail or can, both the 
tank and the pipe will be pretty thoroughly cleaned out. This work must be 
done with great care in order not to lose any of the gasoline during the opera- 
tion. By careful handling the gasoline can be poured back into the tank leav- 
ing the water in your can. There is usually a strainer in the feed pipe and 
this should be kept clean at all times. 

You should know the adjustment of your carburetor. When you are in the 
park or on the road with your company the adjustment of the carburetor will 
always be made by the company mechanic or his assistants. It might happen, 
however, that you are on the road alone without the mechanics and emergency 
adjustments will be found necessary. You must be able to distinguish be- 
tween a Surge in the motor caused by improper adjustment of the carburetor 
and a surge in the motor caused by one or more cylinders not firing. You 
must know that when a popping noise is in your carburetor you have either 
got water or dirt under the needle valve or too thin a mixture. The first thing 
to do would be to drain the bottom of the carburetor and the feed pipe to see 
if water or dirt has gotten in there. If that does not correct the trouble you 
should know how to adjust your needle valve to give a richer mixture. It is 
impossible to show you or to tell you so that you would understand without 
models to demonstrate this. This adjustment and those which I will call your 
attention to later will be given to you in your laboratory and practical work. 
Pay particular attention to the points which I will bring out in this lecture, 
for they are points which we have learned are important in France after one 
year's experience. 

The next point is the adjustment and equalization of your brakes. The 
country over which you will be operating near the front line is very hilly and 
there are constant demands on the brakes. The result is that they require 
almost daily attention. Before attempting to go down a steep or a long hill, 
slow down and shift to first or second speed before getting over the crest of 
the hill. Your engine then acts as a brake and, except in cases where it is 
necessary to make an emergency stop, your foot and emergency brakes will 
have to be used but little. If, for any reason, you do not have time to change 
gears before starting down a hill, use your foot brake for a few seconds and 
then shift over and use the hand brake. Alternate in this way all the way 
down the hill. Never use one brake continually for any length of time as it 
not only wears it out quickly but it is almost sure to get hot and bind. The 
result is that your truck comes to a dead stop and ties up all of the trucks 
back of you. This is a point you must remember. "Above all things keep 
your truck in motion when operating in a convoy." If it is impossible to keep 
it running, pull your truck as far as possible to the right hand side of the road, 
even into the ditch if necessary, so that other vehicles can pass you. How- 
ever, if the brakes are carelessly used and seize, you will find it impossible 

CMC 



Inspection — Lecture II Page 13 

to run your car or even to push it out of the way until the brake drums and 
the lining have cooled off. For that reason you must be doubly careful not 
to have this occur. It is not your own truck alone that you are putting out 
of service temporarily, but you are tying up perhaps five miles of trucks back 
of you. Test your brakes two or three times a week at least to see that they 
are equalized. This is done by jacking up both rear wheels, setting your hand 
brake so that it is just possible to turn the rear wheels by hand, then see that 
the brakes take hold approximately in the same way on both. Then have 
some one sit in the driver's seat and hold the foot brake down part way and 
test both rear wheels to see if the foot brake is equalized. If you are not 
careful about this point your troubles with skidding will greatly increase and 
you will lose a great deal of the efficiency of your brakes. Watch your brake 
lining carefully and anticipate the necessity for renewal of this lining before 
it actually wears out. Due to the almost constant operation in convoy it is 
absolutely essential that your brakes be in excellent shape. Any accident 
which you may have in operating your vehicle in France is investigated very 
thoroughly by a commissioned officer. You as a driver must not only prove 
that the accident was not your fault but you must also prove that it was a 
physical impossibility on your part to avoid it. So you see the importance off 
having your brakes well adjusted and being able to control your car at all 
times so that you will not smash your radiator or have the rear end of your 
truck knocked out. 

The next is the cleaning of spark plugs and adjustment of points and the 
tracing of ignition troubles. Your spark plugs should be cleaned very often, 
at least twice or three times a week. Be very careful in taking them out 
that you do not break the porcelains. If you are careless in the use of your 
monkey wrench or spanner or if you drop the spark plug after you have taken 
it out, you are liable to break this porcelain and you will have to have a new 
plug before you can operate. If you do break a porcelain it is up to you to 
explain exactly how it happened and prove that it was not due to carelessness 
on your part. The actual cleaning of a spark plug and the adjustment of the 
points will be shown to you during your course. I will only dwell on the im- 
portance of keeping them clean and the importance of your knowing how this 
is done. You will also be shown during this course how to trace ignition 
troubles. Ignition troubles should always be turned over by you to the com- 
pany mechanic, with the exception of the cleaning of spark plugs. The ad- 
justing of the points must be done by the company mechanic unless he is not 
around and it is impossible to arrange for him to do it. 

The more you know about your vehicle and the better you know the adjust- 
ments and repairs which must be done on it, the quicker you will get promo- 
tion and reward, and the more service you will render to your company and 
to the Service as a whole. You may think you know all about it but I can 
truthfully state that no one ever knew all there was to know about a truck 
or automobile. Men have made a life study of it and are still learning every 
day. Whenever I hear a driver brag about what he knows and saying that 
there is not a thing about his truck that he does not understand and that there 
are no repairs which he cannot make, I immediately put him down as the 
least efficient of the outfit. Do not brag about your knowledge, but dig in 
and learn it and show it in the operation of your vehicle and in the way you 
keep it up. If you master the three adjustments mentioned above, you will 
have a minimum of difficulty in keeping your truck in service at all times. 

I will outline to you the extent of your responsibility for the motor equip- 
ment placed in your charge. Whenever you are assigned to a truck, a memo- 

c m c 






Inspection — Lecture II Page 14 



randum receipt is made out by your Commanding Officer giving the make and 
type of truck, serial number, motor number and list of all the equipment on 
the truck at the time of transfer. This memorandum receipt is known as 
M.T.C. Form 101. All assignments and all transfers are recorded on this 
form in France. The Unit Truck Equipment is shown on page 92 of the 
Manual and you should be sure that every article called for is actually re- 
ceived before you sign the memorandum receipt. This form is in quadrupli- 
cate and is made out by the person transferring the equipment and is signed 
by the person receiving the equipment. This remains a permanent record 
in the office and is used in checking up periodically for shortages, breakages 
and loss on your truck. Any shortages will be taken out of your pay at the 
end of the month. No excuses are accepted and none should be necessary. 
You are responsible for a good many thousands of dollars worth of Govern- 
ment property. As I have told you many times before, the truck and its, 
equipment are almost impossible to replace in France. That is why you will 
be held pecuniarily responsible for it. Whenever you are relieved of your 
truck and another driver takes charge of it, you must make sure that he signs 
for this equipment and that everything is checked off against the original list. 
If this is not done you may find a few days or weeks later that you will be 
charged up with certain tools and supplies and made to pay for same, whereas 
their loss occurred after you had been relieved from your truck. As you are 
aware, the Army need not consult you about taking money out of your pay 
for loss or damage to Government property. This is something that is beyond 
your control. When you take over a new truck that has been in use by some 
other driver, use all care to see that he does not "put anything over on you," 
as we express it. If he is short of equipment he will try very hard to get you 
to sign for things that actually do not exist. You have got to have your eyes 
wide open and not take his word for anything. 

At all formal inspections your equipment is checked over against the list 
as it appears on M.T.C. Form 101, Memorandum Receipt. These inspections 
are held about once every month and perhaps oftener. You will find it much 
easier and better all around to report loss or damage to equipment immediately 
after it occurs rather than let it slide until an inspection takes place. I know 
this from my own experience. Losses are bound to occur even though you use 
the greatest diligence and care. It is much better, therefore, to report such 
things to the Sergeant Mechanic or Commanding Officer and get it over with 
at the time that it happens rather than take a chance at getting by with it a 
week later when a formal inspection is held. 

When you take your truck to a service park for repairs, all of your equip- 
ment is taken off and checked against your copy of M.T.C. Form 101, which 
is carried with you at all times. This equipment is done in a bundle and 
placed in the stock room for safe keeping. When you return a day or two 
later to take your truck away the bundle of equipment is taken out of the 
stock room and spread out on the ground and rechecked according to your 
list. Any shortages appearing in the equipment when you report to the park 
with your truck are noted, and when you leave the park with your repaired 
truck make sure that you get everything you are entitled to according to your 
list. If tools or supplies have been stolen while your truck was in the park, 
report same at once to the Commanding Officer of the park and insist that 
the stolen parts be replaced before you leave to return to your organization. 
These things that I am telling you are for your own good and most of them 
are things I have learned by hard experience. 

CMC 



Inspection — Lecture II Page 15 

Never allow any other man to drive your truck except the assistant driver 
who is assigned to you. You must make this a hard and fast rule, for if you 
do not, and you allow another man to operate your vehicle and he suffers an 
accident or steals any part of your equipment, you are the one that is held 
responsible for it. 



CMC 



Chassis — Lecture I Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
CHASSIS SECTION 

LECTURE I 

Dismantling 

When a truck or motor car is sent to the shop for repairs, it is thoroughly 
washed of all mud and grease prior to the renewal of the body. After this 
preliminary washing, body and equipment removal operations take place. 
The chassis, which consists of the frame, wheels, axles, in fact all machinery 
connected with the truck, is given another thorough washing so that prior to 
dismantling, the units are fairly clean. Starting with the steering column, 
the first operation is to disconnect the manual spark and gas advance and drop 
the drag link. As soon as this is accomplished, the drop arm proper is re- 
moved and the bolts that fasten the steering column to the side member are 
removed. The steering column is then lifted out. At this point we begin 
the general tearing down of the steering post. Remove sectors on top of 
steering post, also the spark and lever control shaft, and slip out the throttle 
and spark control rods. Extreme care should be taken not to bend the rods. 
Remove steering wheel by taking off large nut at top of steering shaft and use 
soft hammer in tapping off wheel. Slide off steering post housing, and then 
proceed to remove worm and sector gear housing bolts. Clean and examine 
all parts carefully, making sure the keyways and keys are not worn or loose. 
After renewing worn or broken parts reassemble steering gear making sure 
that the bearings fit properly and the gears are not too tight in mesh. 

There are several different types which are used, but the one we will con- 
sider today will be of the worm and sector type. Should the worm be drawn 
too tight into mesh, the post will bind, making steering quite difficult. This 
is eliminated by backing off adjusting nut which is located directly over 
worm and sector housing at lower end of steering post. Should it require 
adjusting for backing, the operation is the opposite ; the nut is carried down 
bringing the teeth of the worm closer to the sector. 

All steering connections from the column forward to and including the 
tie rods and the steering knuckles should be lubricated daily. The ends of 
the reachrods, knuckle pins and parts which are subject to severe vibration 
and wear should be given special attention. 

The worm and sector which are housed in the base of the steering column 
should be lubricated by keeping the casing filled with a heavy oil or packed 
with a soft grease at least weekly. 

The ends of the steering rod are sometimes packed with grease and covered 
with leather boot instead of being provided with grease cups. 

Proper alignment of wheels and lubrication of all steering connections will 
make a difference between easy and difficult steering. The safety of the 
public and yourself depends on the steering mechanism being always in good 
condition. 

CMC 



Chassis — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
CHASSIS SECTION 

LECTURE II 

Springs 

The springs used on a motor truck are generally of the semi-elliptical type. 
The leaves are held together by a center bolt and are secured to the axle by 
spring clips. Since the length of the springs from end to end increases under 
the load, either end or both ends of a spring must be fitted with shackles or 
with sliding surfaces. 

The springs are intended to maintain the proper location of the axles. On 
some makes of trucks radius rods are provided at the rear to keep the rear 
axle in its proper position. On almost all trucks the front springs are provided 
with shackles at the rear end and are pinned to the truck frame at the front 
end and are depended upon to maintain the proper location of the front axle. 

The ends of the springs where the bolts or shackles and pins pass through 
the eyes should be lubricated daily. Grease cups, oil cups or oil reservoirs are 
generally provided. If they are neglected it will be a matter of only a short 
time until the bolts or shackle pins will become worn very badly and the 
drilled oil holes or grooves which are provided will become obstructed. 

When deflection of the springs takes place, the leaves slide slightly one 
against the other, just as the individual cards do when a pack is bent. If the 
leaves are not lubricated, water works in between them and causes rusting 
and pitting. When they have become badly roughened they offer very much 
more resistance to deflection and more of the shock of the road must either 
be taken up by the tires or be transferred to the frame and mechanism of 
the truck. 

Lubrication of the leaves can be accomplished easily if the rebound clips 
are loosened and the frame is jacked up to relieve the springs of the weight. 
The leaves can then be pried apart and a paste of graphite and oil be spread 
between them with a knife. It is possible to get oil such as that which has 
been removed from the engine base to run in between the leaves by applying 
it along their edges. 

The lubricant between the spring leaves will be absorbed in a very short 
time if the truck is operated during wet weather and mud is allowed to dry 
on the springs. In dry weather, the lubricant will last for several months. 

The leaves of a spring are made of a special grade of spring steel, generally 
some alloy steel, and are carefully heat treated to make them tougher and to 
give them greater endurance. Since they are weakened by the hole drilled 
for the center bolt, that is the place where the breakage seems most liable 
to occur. If the spring clips which fasten the spring to the axle are kept at 
all times as tight as possible the bending of the leaves at the center will be 
almost prevented and there will be no danger of their breaking at that point. 
No matter how tightly the nuts on the end of the spring clips are drawn, it 

CMC 



Chassis — Lecture II Page 2 

will be necessary to take them up a small amount from time to time. They 
should be tried at least once a week. 

In the event of spring breakage, a wooden block or a wooden block and 
rubber bumper is placed between the spring and frame or between the axle 
and frame in order to raise the frame to the proper height. The truck should 
then be driven carefully until the spring has been replaced. 

Brakes 

The brakes used on a motor truck are generally of one or the other of two 
types, internal expanding or external contracting. The brake shoes or brake 
bands are generally faced or lined with a material woven like canvas belting 
or like lamp wicking, but consisting chiefly of asbestos, sometimes reinforced 
with fine brass wires. On account of its heat resisting properties this has 
proven to be the most suitable material for brake linings. On a great many 
European and a few American trucks and cars, a cast iron brake shoe is em- 
ployed to work against the steel drum without any lining or facing. 

Brakes are sometimes classified according to the method of operation, as 
hand or foot brakes, also as service and emergency brakes. 

The brakes may be located either in the hubs of the wheels or on the pro- 
peller shaft. The location on the propeller shaft makes it possible for the 
driver to place considerable strain on the universal joints, driving shaft, driv- 
ing gears, differential and axle shafts. When such a brake is used, the parts 
are generally designed with greater strength to withstand this strain. It is, 
however, desirable to use the brakes operating on the rear hubs in preference 
to the transmission brakes under emergency conditions. 

When a loaded truck coasts down a long, steep hill, almost as much work is 
done by the brakes in holding it as would be done by the engine in pulling 
it up the same grade. This results in the generation of a large amount of heat 
in the brake drums and bands. Using the two sets of brakes alternately is 
recommended to reduce the heating effect. 

Two internal brakes placed in the same drum will afford better cooling 
than one inside brake and one outside brake, if the inside and outside brakes 
are both applied on the same drum at the same time on a long hill. It is 
especially difficult for the heat generated to escape and the linings and drums 
are liable to become overheated. 

On a few trucks where internal brakes are used, the drums are provided 
with cooling fins similar to those on the cylinders of a motorcycle. Before 
modern asbestos brake linings had been developed, several European cars 
employed a water dripping device which operated when the brakes were 
applied to keep them cool. 

Relining of Brakes 

To reline brakes, jack up rear axles and remove wheels. Sometimes the 
brake shoes can be taken off without removing wheels. 

Remove old lining by taking a sharp chisel and cutting off the heads of 
copper rivets. 

In replacing new lining, care should be exercised in selecting the proper 
material (see manufacturer's specifications), proper length, width and thick- 
ness is required for each brake. Place lining on brake shoe and drill small 
holes using the old holes as guides. Then remove lining and countersink to 
about one-half the thickness, therefore allowing rivet heads to sink sufficiently 

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Chassis — Lecture II Page 3 

in lining and to retain a firm grip on same. When replacing brake shoes be 
careful to allow clearance space ; for should they bind, it will cause consider- 
able damage and strain on every part of the mechanism of chassis. The drum 
will become very hot and in cases where wooden wheels are used cause con- 
siderable damage and a continual drag on the motor. 



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Chassis — Lecture III Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
CHASSIS SECTION 

LECTURE III 

Clutch 

In order that the power plant of a motor truck may be started and kept 
running, but still permit the car to remain stationary, it is quite important 
that some mechanism be provided for this purpose. Likewise, if we desire 
to maintain a certain engine speed, but require a greater speed of the vehicle, 
means also must be provided to permit the changing of gears. For example : 
Assuming that we are in first speed and the truck is moving five miles per hour 
and the engine R.P.M. is 900, and we desire to go to second. The difference 
of speed of gears would not permit them to mesh. This mechanism which al- 
lowed for the above mentioned requirements is called the clutch. As a result 
of experience the friction clutch is universal. 

These devices are capable of transmitting any amount of power if properly 
proportioned, and permit a gradual engagement and a positive disconnection. 
Most friction clutches are simple in form, easily understood, and may be kept 
in repair and adjustment without difficulty. 

The main object in designing a clutch is to increase the amount of friction 
existing between the parts to as great a degree as possible. The transmitting 
efficiency of the clutch will vary with the coefficient of friction between the 
surfaces, and the more friction between them, the more suitable the clutch 
will be for transmitting power. A metal usually forms one frictional surface 
in all forms of clutches, and some types have been designed and used success- 
fully, in which all frictional surfaces are metal. 

The materials used generally for the metallic plates are cast iron, alum- 
inum and bronze castings and sheet steel and bronze, usually in the form of 
thin stamped discs. The non-metallic frictional materials generally used are 
leather, asbestos fabrics, textile belting and cork. Leather is the best lining 
or facing for clutches where the frictional area is lai'ge. When used it must 
be kept properly lubricated and soft, if it becomes dry it will engage very 
suddenly and the clutch action will be harsh. On the other hand too much 
lubricant must not be applied or the clutch will slip. Oak tanned leather 
which is generally used because of its good wearing qualities, is a very re- 
silient material and possesses a satisfactory degree of frictional adhesion 
when pressed against a cast-iron member. Asbestos fabrics are being applied 
in many forms of dry plate clutches and have been used to some extent in 
facing the male members of some clutches. These are not as elastic as leather. 
When cork is used it is inserted in the metal surface in suitable holes which 
are machined to receive the inserts. Cork possesses peculiar qualities which 
make it suitable for use in a clutch. It has perhaps the highest coefficient of 
friction of any of the materials employed and is not materially affected by 
either excessive lubrication or the lack of it, and possesses desirable wearing 

CMC 



Chassis — Lecture HI Page 2 

qualities. In application, cork must be used in inserts, because it is too 
brittle to be used in sheet form with any degree of success. 

The proper use of the clutch is of importance from the mechanical stand- 
point, as improper use will necessitate repair and readjustment. The clutch 
should always be either engaged or disengaged. Do not drive with the foot 
on the clutch pedal. The weight of the foot on the pedal and a little nervous 
tension of the driver's leg is sometimes just sufficient to hold the clutch out 
far enough to "slip it" on a hard or sudden pull. Another way to spoil a 
clutch is to throw it out in traffic until the car comes almost to a standstill — 
then to speed up the engine and slip the clutch in with the gear lever still in 
high speed. When the car slows down with the clutch out, the gear lever 
should be shifted to second speed and if the car comes to a complete stop, 
should be shifted to low speed. Another important point in the proper use 
of a clutch is to engage the clutch gradually and not to bring it in with the 
engine racing. It is always better to run on the engine as much as possible, 
throttling it down, instead of constantly throwing out the clutch. 

One of the simplest forms of clutch is the cone clutch. This consists of a 
metallic cone covered with leather or other frictional material ; a clutch spring 
which holds the tension of the cone to the flywheel ; pressure or plunger studs 
which are spring mounted and placed under the clutch leather at various 
points and allow gradual engagement of the frictional surface ; clutch rollers 
on the shifter yoke; ball thrust bearings on the clutch shaft which prevent 
spinning of the clutch. 

Cone clutch troubles can be divided into two distinct divisions: fierce en- 
gagements or grabbing, and slipping or spinning. 

There are several causes for the clutch grabbing. A dry or hard clutch 
facing will produce this and can be remedied by an application of neat's-foot 
oil. The leather should first be cleaned with kerosene. Projecting clutch 
rivets also cause grabbing. This is indicated by a grating or grinding sound 
in the clutch and can be remedied by placing a center punch against the rivet 
head and hammering until the head is below the surface of the leather. Clutch 
lever linkages out of adjustment will also cause this trouble. The amount of 
movement between the surfaces of the clutch is small and it is important that 
no looseness exist in the pedal connection. There should not be excessive 
tension on the clutch spring as this will cause weakening of the spring and 
also bring an undue strain on the ball thrust bearings. If pressure or plunger 
studs are employed under the clutch facing, care should be taken that they 
are properly adjusted. The clutch rollers on the shifter yoke may be worn, 
due to lack of lubrication. If they run dry they are liable to seize and prevent 
the clutch from releasing entirely. In this case new rollers must be fitted. 

There are also quite a few conditions that contribute to clutch slipping. 
A burned or worn out clutch lining will cause this and usually results from 
allowing the clutch to slip when starting or changing speeds, or from using 
the clutch too much instead of throttling the motor down. Even though worn 
to a certain extent the application of neat's-foot oil will improve its operation. 
If the neat's-foot oil does not produce the desired result a new clutch facing 
must be installed. A cone clutch will also slip, due to the clutch leather being 
oily and greasy. The cure is to wash the oil off by spraying kerosene and 
then dress the leather afterwards with neat's-foot oil. The oil can also be 
absorbed by using powdered Fuller's earth, which is sprinkled over the surface 
and allowed to stand for several hours. Do not use dirt or sand to prevent a 
slipping clutch as this will cut the leather. If the leather is worn down and it 
cannot be raised enough by adjusting the plungers to make it firmly grip the 

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Chassis — Lecture HI Page 3 

metal it is usually necessary to replace the facing. However, it will some- 
times be found that the clutch is not fully engaging and at the point of its 
engagement in the flywheel, a ring has been worn in the leather. This ring 
can be dressed down with a rasp which will usually allow the clutch to engage 
deeper in the flywheel and a good clutch can be obtained without replacing 
the facing. Weak clutch spring tension will also cause the clutch to slip. In 
this case the adjustment must be tightened. If there is no adjustment pro- 
vided the tension can be increased by placing a washer between the spring 
and its seat. Slipping is also caused by the clutch shaft being out of line. 
This is many times due to too great a spring tension causing the balls to break 
in the thrust bearing and cutting the ball race, lowering the clutch shaft out 
of line. It also may be due to a bent clutch shaft or lack of alignment. 

Clutch spinning is often due to excessive friction in the spring thrust bear- 
ing, though sometimes faulty alignment of the flywheel and clutch cone will 
prevent the engaging surfaces from entirely clearing each other. A bent 
clutchshaft might also be the cause of this. Sometimes the fault lies in the 
clutch. A heavy rim or cone will store up energy and continue to revolve 
when disengaged. When a clutch spins from a lack of alignment or adjust- 
ment the remedy is obvious, but if the fault is in the design, a clutch brake 
should either be fitted or the clutch rim lightened by drilling or machining 
away the metal at or near the outer circumference. 

It is necessary to lubricate the moving parts of a clutch, the rollers or 
clutch yoke and the ball thrust bearings, but it is essential to its operation 
that lubricating oil be kept from the clutch facing as much as possible, as this 
type of cone clutch is supposed to run dry, except for the application of the 
necessary neat's-foot oil to keep it flexible. 

Sometimes a clutch will fail to release and this is known as a "frozen 
clutch" and is usually due to a rusty or tight pedal connection or loose pedal 
link connection. Clutch yoke rollers run dry, sometimes from too tight a 
spring adjustment. 

Excessive wear makes it necessary sometimes to replace the clutch facing. 
Usually the manufacturer can furnish suitable clutch facings or leathers, 
which are fastened at the ends and cut to the proper size. After the old fac- 
ing has been removed, the new one can be forced upon the clutch web. The 
easiest way to accomplish this is to first soak the leather over night in water, 
which will make it possible to stretch the same into position. When the leather 
shrinks it will fit very closely and can be riveted in place without any diffi- 
culty. The rivets should be countersunk at least -fa " below the surface of the 
leather. Be sure, before replacing a clutch leather, that the cone itself is 
true. If the cone is out of true it should be turned true in a lathe. How- 
ever, if it is only out of true .002" or .003", it may be turned true after the 
clutch leather has been installed, cutting away enough of the leather to make 
up for this defect. Before attempting to replace the clutch facing be sure 
that the replacement is absolutely necessary. Many times, by repairing the 
old facing a better clutch will be obtained than if a new one is installed. 

The disc clutch, or multiple disc clutch, consists of a number of discs which 
are pressed together when the clutch is in, the friction between them causing 
one to drive the other. This type of clutch is very compact. To illustrate the 
principle of the disc clutch, place a silver dollar between two silver half- 
dollars and squeeze them together between the forefinger and thumb of one 
hand. With the other hand try to revolve the dollar, not moving the halves. 
It requires only a slight squeeze to produce sufficient friction to make it im- 
possible to move the dollar. 

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Chassis — Lecture HI Page 4 

The lubricated multiple disc clutch is generally so constructed that steel 
and bronze plates alternate and are held in contact with a strong spring. 
This type of clutch sometimes slips, due to the oil in which it operates becom- 
ing too thick or gummy. The process of eliminating this is to, first, drain the 
oil out of the clutch; second, wash well with kerosene, placing the kerosene 
in the clutch and, while the motor is running, engage and disengage the discs 
by pressing on the foot pedal. Then remove the kerosene and fill the clutch 
to the specified level with clean oil. Some manufacturers recommend that 
cylinder oil and kerosene in equal portions be used to make the oil bath in 
which these clutches run. The spring tension must be properly adjusted as 
this is many times the cause of the clutch slipping. However, the tension 
must not be too great as this will cause the clutch to grab. 

The dry type of multiple disc clutch in construction is very much the same 
as the lubricated type except that one set of the discs is faced with some 
sort of friction material, such as Raybestos. These plates alternate with the 
metal ones, which are usually of steel. 

The slipping of this type of clutch is often caused by the lack of proper 
clearance between the clutch opening fingers and the release plate. 

The clearance should never be less than tV " or more than Vs " when the 
clutch is in. This necessitates the adjustment of the clutch opening fingers. 
Another cause for slipping is too little tension on the clutch spring. Never 
tighten the clutch spring nuts until the release fingers have been adjusted to 
the proper clearance. Neither of the above-mentioned adjustments would 
have any effect if the lining on the discs is worn so thin that the clutch casing 
seats on the flywheel. When worn thus the clutch must be removed. An ex- 
cess of oil on the clutch facing would also cause the clutch to slip and should 
be carefully cleaned off. This can be accomplished by washing with kerosene 
or gasoline. Continual slipping causes the discs to get very hot, warping the 
steel discs and raising the rivets on the lined discs so that they cause the clutch 
to chatter, with the possibility of grooving the discs and giving them a per- 
manent warp. A noisy clutch, particularly when released, is usually due to 
a worn clutch thrust bearing and replacement of the bearing is necessary. 

To remove the clutch it is necessary to remove the bolts on the clutch cross 
shaft and spring it up. Then remove the clutch cross shaft and the nuts that 
hold the clutch spring bolts. These bolts must also be removed. Then pull 
the clutch out and remove from the frame. Place the ring assembly on the 
bench with the clutch rings up and remove the snap ring. Then remove all 
of the friction plates, noting how the rings are removed so that they may be 
again built up in the proper sequence. Clean all parts with gasoline and 
scrape out the clutch ring recesses both on the flywheel and the clutch hub. 
If the asbestos faces on the discs are worn they must be replaced. The split 
rivets holding them should be opened down below the surface, if the facing 
does not have to be removed. To replace the facing, cut off the head of the 
old rivets, taking care that the discs are not sprung out of shape in so doing. 
Examine each disc to see that it is not sprung or warped out of shape and 
note whether the steel discs are grooved. If either is the case the discs must 
be replaced. Using each disc as a template, drill the rivet holes in the new 
facings, countersinking slightly for the rivet heads. The new facings can best 
be obtained from the car maker and this should be done if possible. Using 
solid copper rivets, rivet the new facing to the disc. Examine ball and roller 
bearings of the clutch for wear and the clutch bushings for looseness. Re- 
place with new ones if any amount of wear is evident. In assembling the 
clutch make certain that the rings are inserted in the proper relation to each 

CMC 



Chassis— Lecture III Page 5 

other. In assembling the clutch it is necessary to use some sort of clutch 
spring compressor. Different types of compressors are suggested by various 
manufacturers or an arbor press, or even a vise can be used to advantage. 

If the clutch starts to slip, adjust it at once. Do not allow a clutch to be 
used in a slipping condition. Use no oil in the interior of this type of clutch, 
except on the bearings, and these should be carefully oiled, making sure that 
none of the oil has an opportunity to work into the discs. Do not drive with 
the foot on the clutch pedal. 

The plate clutch is one where one plate is clamped between two others. 
The single plate clutch is a popular type of clutch. It is a variation of the 
disc type, the latter comprising a large number of narrow discs, while the for- 
mer usually consists of but three broad discs or plates, the ordinary type hav- 
ing two driving plates and one driven plate. This clutch, like the multiple 
disc type, is of both the lubricated type and the dry. The adjustments of 
these types vary in all different makes and are specified by the manufacturers. 
The causes for trouble and their remedies are practically the same in the 
multiple disc type. 

A universal joint is a flexible connection between two shafts which permits 
one to drive the other, although they are not in line. Universal joints are 
usually placed in front and rear of the drive shaft. They are necessary on 
automobiles with shaft drives, for while one end of the driving shaft is at- 
tached to the transmission-shaft, which is on the frame, the other end is con- 
nected to the axle, and is constantly moving up and down as the wheels follow 
the uneven contour of the road. In other words, the driving unit or engine 
is in one plane and the driven unit or axle is in another, and the universal 
joints make possible the transmitting of power from one plane to another. 
If no universal joints were used, the shaft would jam in its bearings from the 
up and down motion. 

Various types of universal joints have been devised to take the place of 
the modified Hookes coupling which is so widely used in transmitting motion 
from the power generating engine to the rear construction of the modern 
automobile. The "spring plate" and the "leather disc" have both been used 
with some degree of success, but the majority of manufacturers have adhered 
to the first mentioned type, which has been most successfully developed by the 
Spicer Manufacturing Co., and is known as the Spicer Universal Joint. 

The universal joint is an important element in practically all shaft drive 
cars, some constructions using but one joint, if the propeller shaft is pro- 
tected by a long housing, while other systems employ two universal joints, 
one at each end of the exposed propeller shaft. Universal joints on many 
eai'ly cars were run exposed and considerable trouble was experienced due 
to the rapid wear of the bearing parts. When exposed there was considerable 
difficulty in keeping the joints properly lubricated. The modern forms are 
housed inside of a casing member, which is not only designed to exclude the 
dirt and grit from the bearing surfaces, but which is also depended upon to 
retain the lubricant. 

Because of the adoption by many manufacturers of universal joints which 
correspond closely with the Spicer Universal Joint, that type of joint will be 
used as an example in discussing the care and repair of same. 

Every 1000 miles the grease hole plugs should be removed and the joint 
properly greased. The kind of grease recommended by different car manu- 
facturers varies, but the oil known as "timing gear oil" having a consistency 
between heavy cylinder oil and vaseline, may be used in most cases. Graphite 

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Chassis — Lecture HI Page 6 

grease also makes a good lubricant. Do not use too much grease or it will 
have a tendency to work out, the centrifugal forces of the revolving joint 
throwing it all over the surrounding portion of the car. The joint should 
be filled about § full. 

The forward universal joint, when two joints are used, is provided with a 
dust cap and felt washer on the rear end of the sleeve into which the end of 
the propeller shaft slides. This cap should be turned to the right occasion- 
ally in order to keep the felt washer tight and prevent the leakage of grease. 
Both joints have flax packing between the two parts of the pressed steel cas- 
ings. The packing can be tightened by loosening the binding screw and turn- 
ing the casing, adjusting nut or ring in the right hand direction. If grease 
works through the packing in the front universal joint, the joint will not only 
suffer from lack of lubrication but the grease is apt to be thrown into the 
brakes, rendering them inoperative. 

When the universal joint has been disassembled and is being assembled 
again, care should be taken to see that the holes in the flange and the inside 
casing are matched up in such a way as to bring the oil hole, which is closed 
by a threaded plug, opposite an open space in the joint, and not opposite one 
of the lugs, which would prevent the introduction of grease through the hole. 
The purpose of the grease hole is to allow examination of the lubricant within, 
and the injection of oil or grease at any time by the use of an ordinary 
grease gun. 

Sometimes these joints are incased in a leather boot and in cleaning the 
joint it is necessary to remove this. This joint should then be washed with 
gasoline or kerosene. In some cars the housing enclosed by the leather boot 
is a small cylindrical sleeve held by four set screws. When these are removed, 
the sleeve may be slipped off the universal joint, leaving this free to be 
cleaned. The used oil should be removed entirely and new grease put in. 

Should a knock or rattle occur in the joint, it is a case that necessitates 
disassembling and rebushing of the working parts. If the wear is so extensive 
as to cause an excessive "back lash" when applying the power or the brakes, 
it is advisable to replace the worn joint with new ones. 



C M. C 



Chassis— Lecture IV Fa 9 e 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
CHASSIS SECTION 

LECTURE IV 

Transmission 

The principle of the transmission is to allow the engine to speed up until 
the energy which is stored up in the flywheel is sufficient to keep the shaft re- 
volving at a speed showing no great percentage of variation. A second and 
principal duty is to adapt the engine to a heavy load, which, under the circum- 
stances, would cause it to slow down and stall if required to work under such 
conditions any length of time. 

For example, it may be assumed, that a man is raising a bucket of water 
from a well by winding a rope around the drum of a windlass. The bucket 
must be raised a certain number of feet every minute. Then if the bucket of 
water weigh such an amount as to require all of his strength to fulfill these 
conditions, and that any extra weight added to the bucket would overtax his 
strength to such an extent as to make further progress impossible, it is evident 
that some mechanical contrivance is necessary which will enable him to exert 
the same strength, but apply it through a longer period of time. To make this 
plain, it may be assumed that he wished to lift a barrel weighing six hundred 
pounds ten feet. It is evident that this could be not be done in a direct manner. 
If, however, he should build an incline long enough he would be able to roll it 
up, accomplishing the same work, but taking a longer time. Another way 
would be to use a lever. 

Now, returning to the first illustration, instead of turning the drum of the 
windlass direct by hand, a gear may be placed on the end of the drum and con- 
structed to mesh with a smaller gear attached to the lever. To illustrate the 
principles involved, it may be assumed that the large gear on the drum is three 
times the diameter of the small gear. It will, therefore, require three revolu- 
tions of the small gear to one of the large gear, and the pressure exerted will 
be only one third of that required if the crank were fastened to the drum direct. 
To compare this with the conditions of automobile operation, the work required 
to lift the bucket may be represented by the work required to drive the machine, 
and the man's effort or force applied to the lever of the windlass by the pres- 
sure exerted on the piston of the engine. Transmissions may be divided into 
three classes: the friction drive, the planetary, and the sliding gear trans- 
missions. 

The "Friction-Drive" type is practically obsolete, and consisted of a large 
disc, turned by the engine, and a large wheel at right angles to the disc, the 
wheel turning a "Jack Shaft" from which the rear wheels were driven by 
sprockets and chains. The wheel could be moved sideways on the "Jack Shaft" 
by a lever and pressed against the disc, or released from it by a foot pedal. 
When the wheel was moved near the center of the disc, and pressed against it, 
it turned slowly. When it was moved near the outer edge of the disc, it turned 
faster. The chief trouble with this type was "slipping," wearing out of the 
leather facing of the wheel and wearing out of the bearing which supported 

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Chassis — Lecture IV Page 2 

the disc-shaft, due to the fact that, when running, the wheel was forcibly held 
against the disc near the edge, and caused a side-thrust on the shaft. 

The "Planetary" type is used almost exclusively on the Ford and has only 
two forward speeds and "reverse." The flywheel has three studs, each of 
which carries three gears of different sizes fastened together to form what is 
called a "triple-gear mesh" with three gears of different sizes in line with the 
engine-shaft. The inner one, next to the flywheel face, is fastened to the drive- 
shaft which delivers the power through to the rear axle. The other two central 
gears float on the drive shaft and are connected to the two drums nearest the 
engine. Surrounding these drums are brake bands which can be tightened by 
foot pedals. If the slow speed (middle) drum is held, the second (middle) of 
the three central gears around the engine shaft will be held stationary. This 
makes the triple gears rotate on the studs as the flywheel revolves. In doing 
this, they drive the first central gear, which is located nearest the flywheel and 
fastened to the drive shaft, slowly forward due to the difference in the sizes 
of the gears. If the middle drum is gripped instead, by pushing on the re- 
verse pedal, the larger of the three central gears (third from the flywheel — 
around the drive shaft) is held. This makes the triple-gear revolve again on 
the studs as the flywheel revolves, but since this reverse gear is larger than the 
driver gear, the motion of these triple gears will turn the driver shaft slowly 
backward. For high speed, the entire mechanism is gripped solidly together so 
that it revolves at engine speed. A multiple disc clutch is used to engage and 
disengage the direct drive. A third drum is used for the service brake. 

This mechanism very seldom needs repair, with the exception of the replace- 
ment of the transmission bands, the linings of which wear out in a compara- 
tively short time. To replace these, remove the transmission case cover, first 
loosening the adjustment of the bands so that the cover will slip off easily. 
The bands may then be removed one at a time by sliding them close to the 
flywheel, and turning them around on the drum, so that the ends are at the 
bottom. The old bands may be relined, or as is customary, new bands with 
the lining already attached may be put on. If the old bands are to be relined, 
use plain brake-lining only. Never use a lining which has the fine copper wires 
in it, like "Raybestos," as the little pieces of wire are apt to cause short cir- 
cuit in the magneto, which is enclosed in the same housing. After the new bands 
have been slipped onto the drum they should all be turned so that the ends are 
in line at the top. In order that the adjusting screws and springs will come 
into proper position with the ends or lugs of the bands when the cover is put 
on, the ends of the bands must be squeezed together as far as possible, and 
clamped, or wired to hold them while the cover is replaced. A new felt gasket 
should be used under the cover to prevent oil leaks. After the cover is in 
position, the clamp or wire around the band ends are removed. 

The adjustment of the clutch is very simple, and is accomplished by turn- 
ing the adjusting screws on the clutch fingers. 

Noisy action of low speed and reverse gears usually mean worn out bushings 
on the flywheel pins around which the triple gears revolve, or the pins them- 
selves may be loose. If repairs or replacements to these internal parts are 
necessary, the engine must be removed from the frame, the crank case re- 
moved, and the transmission disassembled. The bushings on the inside of the 
drums should be examined for wear, and new drums replaced if any appre- 
ciable "play" is noted. 

The "sliding gear" type of transmission, commonly called a "Gear-set," is 
used on practically all trucks. The transmission case contains two shafts, a 
main shaft which is either square or "milled," so that gears may slide back 
and forth on the shaft, but must turn around with it, and a second, or counter 

CMC 



Chassis— Lecture IV p <*ge 3 



shaft, on which several different sized gears are keyed. By means of a lever, 
the gears on the main shaft may be meshed with those on the counter-shaft and 
the various speeds obtained. 

The main shaft is not a continuation of the clutch shaft, but turns inde- 
pendently inside the clutch shaft in a bushing. The clutch shaft turns the 
gear just inside the case, which is always in mesh with the gear on the counter- 
shaft. Therefore, the main shaft does not turn when the clutch shaft and the 
countershaft are turning, unless one of the sliding gears on the main shaft is 
meshed with a gear on the countershaft. In the gear set shown, first, second 
and third speeds would be obtained by sliding the gear on the right of the main 
shaft against the driving gear on the end of the clutch shaft. Both of these 
gears have "dogs" on their sides which engage when the gears are brought to- 
gether. In this case, the countershaft is not used, and the position is called 
"direct drive." The principle is the same in a three speed transmission, direct 
drive being third speed instead of fourth. "Reverse" is obtained by meshing 
one of the sliding gears with a small "idler" gear, which is turned by the 
countershaft. As the power is transmitted from the countershaft to the main 
shaft through an intermediate, or "idler" gear, the main shaft will be reversed. 
When changed from one gear to another, the clutch must be disengaged so that 
the gears are free from strain. 

The sliding gears are moved by means of "shifting forks," moved by rods 
connected to the gear shift lever. These forks slip into "collars" on the side 
of the gears. Careless drivers sometimes try to force gears into mesh with 
the result that these forks are bent and the gears cannot be meshed, or un- 
meshed. In this case, the transmissions case cover must be removed, together 
with the shifting mechanism, and the fork straightened. 

To prevent the gears from sliding about on the main shaft independently 
and to hold them in whatever position they may be placed, grooves are made in 
the shifting rods at the proper positions, so that a pointed "finger" under 
spring tension, snaps into the groove, and holds the gear firmly in position. 
Occasionally, these fingers will stick on account of dirt, or a little roughness, 
and will make shifting difficult. They can be easily removed and cleaned up 
by unscrewing the plugs over them. 

The sides of the gear are chisel-faced, to make engagement easy. How- 
ever, by constant use, the set may become "burred" and a noisy engagement, 
or "clashing" of the gears will result. It is then necessary to remove the gear 
and grind the edges smooth on an emery wheel. Worn gears, and worn bush- 
ings at the ends of the shafts are also sources of loud "grinds," and noisy 
operation. "Stripped" gears are usually the result of careless driving, the 
gears being "crashed" into mesh, while the clutch is partially, or entirely en- 
gaged. A clutch so adjusted that it does not drag, and a clutch-brake that 
is so aranged that the clutch shaft stops revolving at once, will go far toward 
avoiding the clashing of gears in shifting and the prevention of transmission 
trouble in general. If it is necessary to repair or replace gears or bushings, 
the transmission case must usually be removed from the car. The top is re- 
moved, to which are fastened the shifting rods, and forks. The two shafts can 
then usually be removed by taking off one or more plates at the front of the 
case. In some cases, the whole end can be removed, although of course con- 
structions vary. 

As to lubrication of the transmission, always try to follow the instructions 
of the manufacturer. In general, a light "fibre" grease is best. Never use 
"cup-grease" in the transmission, or differential, as it breaks up, and loses its 
lubricating qualities. Any stiff, or butter-like grease will be thrown from the 

CMC 



Chassis — Lecture IV Page 4 

gears by centrifugal force, so the ideal lubricant should be molasses-like, and 
flow over the gears without being thrown. The oil drained from the engine is 
"waxy," and makes a good transmission lubricant after it has been strained, 
and mixed with a little "fibre" (transmission) grease. 

Wheels 

The wheels of the modern motor truck must be of especially sturdy con- 
struction, as they not only carry the heavy loads, but must also be able to 
withstand much greater strains, side thrusts, and hammering action which 
they receive when the truck is hammered around turns by driver on very rough 
roads. The driving wheels, in addition, must be capable of withstanding the 
driving effort of the truck. 

Wooden Wheels 

The wheels which have been used most commonly are built with metal hubs, 
wooden spokes and felloes, and steel rims. The objection to wooden wheels 
for truck purposes is that during extremerly dry weather the spokes will be- 
come loose, and if the machine should take fire, the wheels are liable to be 
destroyed, which makes it a very difficult matter to handle in taking the wreck 
to the repair base. If the hub bolts on wooden wheels show signs of looseness, 
special care should be taken to keep them tight; should the wooden wheels be 
operated with loose spokes they will have a very short life. A noticable effect 
will be a creeping of the wooden spokes. 

Metal Wheels 

During the past few years the cast wheel for truck purposes has been gaining 
popularity. The construction may be with hollow spokes resembling the wooden 
wheel. Others may be in the appearance of wheels used in agricultural ma- 
chinery. Cast steel wheels are also sometimes used in the form of discs, some- 
what similar to wheels used on locomotives. 

Some disc wheels for trucks are built out of sheet steel and being strong and 
light are in every way desirable. Wire wheels, although especially desirable 
for passenger cars are not built sufficiently strong for satisfactory work on 
trucks. 

Ball and Roller Bearings 

Whenever the shaft turns in plain bearings, or one surface moves against 
another with a pure sliding motion, there will be at least a small amount of 
friction. No matter how smooth or highly polished the surfaces are made there 
will still be the fluid friction due to the molasses-like quality or viscosity of 
the lubricant. Ball or roller bearings are generally used in the wheels, axles, 
transmission, and some other parts. 

The loads which a bearing must carry are referred to as radial load, that is, 
a load at right angles to the length of the shaft, and thrust load, that is, the 
pressure or load acting parallel to the length of the shaft. 

Types of Ball Bearings 

Ball bearings are classified under various names according to the kind of 
loads which thy are designed to carry. Cone and cup ball bearings like those 
used in the wheels of a bicycle or the front wheels of a Ford are capable of 
withstanding both the radial and thrust loads. 

CMC 



Chassis— Lecture IV P&9 e 5 



When bearings are not required to carry any appreciable end thrust they 
may be arranged for the balls to roll between two races placed one inside of 
the other, a suitable shallow groove being ground on the outside of the inner 
race and another one on the inside of the outer race. Such a bearing, called 
an annular or radial bearing and used very commonly in transmissions, is some- 
times used in rear axles or rear wheels, and is occasionally used on the crank 
shaft of an engine (the White), or in front wheels. 

When a bearing is to carry end pressure only, the balls may be arranged be- 
tween two parallel discs. These discs may be absolutely flat with some pro- 
vision made for keeping the balls in proper position or they may be grooved 
slightly. Such bearings are sometimes used behind bevel or worm gears and 
on the steering gear to carry the end thrust. 

A device known as a cage, a retainer, or a separator is used in most ball 
bearings in order to separate the balls a short distance from each other and 
to prevent a rubbing contact of one against the other. 

If one ball in a ball bearing becomes pitted or cracked it is not safe to substi- 
tute another one as it will probably be larger than the rest of the set. 

Types of Roller Bearings 

Roller bearings are usually classified according to the shape of the rollers, 
as straight or tapered. 

Where there is no end thrust, plain hardened steel cylindrical rollers gen- 
erally of comparatively short length, running between two ground hardened 
steel races are sometimes used. Straight rollers with flanged ends are used 
to some extent where a small thrust load must be carried. 

The most common form of straight roller bearing, the "Hyatt' bearings, has 
rollers which resemble springs wound out of flat steel instead of round wire. 
For use in the gear box and other places where hardened races may be em- 
ployed short rollers are most frequently used. For use between the axle shaft 
and rear axle housing in cheap cars the rollers are generally 2V 2 to 3 inches 
long. These bearings are non-adjustable and give very satisfactory service. 
If they are not provided with hardened steel races they are rather short lived 
but inexpensive to replace. 

For use in the gront wheels of any motor vehicle and for use in all the 
wheels of a heavy truck, the tapered form of roller bearing has been found to 
be the most satisfactory. Such a bearing is capable of supporting a radial 
load many times as great as a ball bearing with balls of the same diameter. 
At the same time it can carry a heavy end thrust successfully. Unless an inex- 
perienced driver or mechanic draws the adjusting nut up too tightly or water 
or sand, are allowed to work into such a bearing, it should last as long as the 
truck. 

Care and Lubrication of Bearings 

All ball and roller bearings should be kept at all times properly lubricated 
with oil or a very light-bodied grease. If there is friction between the balls or 
rollers or between them and the retainer, it will cause wear and cutting. 

Felt washers are generally fitted or other suitable provisions are made to 
keep sand and water out of the ball or roller bearings. In the front wheels 
these felt washers should be examined from time to time and if necessary 
renewed. 

CMC 



Chassis — Lecture IV Page 6 

Wheel bearings should be removed, washed with kerosene and repacked with 
cup grease every two thousand miles or as directed by the manufacturer. 
Especial care should be taken in mounting or adjusting any ball or roller 
bearings. Tapered roller bearings in wheels should not be drawn up with a 
wrench tight enough to bind, but when locked should have a barely perceptible 
play or shake. Generally the wheel will be loose enough to rock back and forth 
if given a slight start. The manufacturer's instructions concerning mounting, 
adjustment, care and lubrication should be followed. 



CMC 



Chassis — Lecture V Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
CHASSIS SECTION 

LECTURE V 
Differential 

The most common form of differential is designed to equalize the turning 
effort of both driving wheels even though they are turning at different speeds, 
as in rounding a corner. Figures 1 and 2 (see Plate I, Lecture V), represent 
an ordinary bevel gear type of differential. Power is applied through the 
driving pinion to the bevel driving gear, sometimes called a bevel ring. This 
is bolted or riveted to a flange on the differential casing. Mounted in the dif- 
ferential casings are two differential side gears, each of which is attached to 
one of the axle shafts by a square or spline fit, or sometimes by key. A cross 
or set of studs is mounted between the two halves of this differential casing. 
Mounted on the arms of this cross or on the studs, and free to turn around, 
there are small bevel pinions which mesh with the two differential side gears. 
When one wheel runs faster than the other the pinion turns to give the neces- 
sary compensation in speed between the two differential side gears. 

Another form of equalizing differential, known as a spur gear type, accom- 
plishes the same purpose as the differential which employs bevel gears. It 
makes use of spur gears for the axle shafts as pairs of spur pinions meshing 
together instead of bevel pinions. 

The weakness of the ordinary form of differential lies in the fact that as one 
wheel only has traction, all that can be accomplished will be a spinning of that 
wheel. The wheel which has traction will receive no more pull than that re- 
quired to spin the easier moving wheel. To eliminate this difficulty there have 
been designed differentials which are sometimes classified as over-running or 
as the over-wheel type. The mechanism is so arranged that the power is ap- 
plied always to the slower moving of the two wheels. On a turn this applies 
all the power to the inner wheel and allows the outer one to run free. If one 
wheel has poor traction both wheels will be driven at the same speed just as 
if they were mounted on a solid axle. 

Some of the earlier designs of differential were faulty because there was too 
much back-lash and lost motion in the mechanism which could be taken up with 
a sudden jerk. 

Another form of differential employs worm instead of bevel gears for the 
equalizing mechanism within the differential case. It is intermediate in action 
between the equalizing and the over-running types and it has some of the 
advantages of both. 

On a few makes of trucks a device known as "differential lock" has been pro- 
vided so that the driver, by applying a convenient pedal lever could lock the 
differential and secure the same effect as would be obtained with a solid axle 
shaft. 

The term dead axle applies to an axle which is stationary. The wheels are 
mounted on spindles and are driven by side chains, the differential being lo- 

CMC 



Chassis — Lecture V Page 2 

cated on the forward shaft, known as a countershaft or jack shaft. Chain 
drive for motor trucks is losing popularity the same as it did several years 
ago on passenger carrying cars. 

The term live axle is often used to cover all types of axles which contain 
revolving drive shafts. The axles used in most of the heavier trucks purchased 
by the Government are of the type known as full floating. The hubs of the rear 
wheels are provided with two bearings each and are mounted on the outside 
of a tubular rear axle housing. The inner ends of the axle shafts fit into the 
side gears of the differential. The outer ends are provided with flanges either 
integral or securely attached, which are bolted to the wheel hub (or in some 
cases are notched and held in place against the notch head of the hub cap). 
When the power is applied to the differential by means of the bevel or worm 
gears, the axle shafts are carrying the turning effort necessary to drive the 
rear wheels. The axle shafts support the dead weight and are subjected to no 
binding strain, their only duty being to drive the wheels. The axle housing- 
serves to support the weight and carry any binding and straining. 

The design of the full floating axle is generally such that the axle shafts and 
the differential may be removed and the truck may be left standing supported 
by its own wheels. 

The term semi-floating applies to the type of axle where the rear wheels 
are keyed to the tapered ends of the axle and the axle shafts are depended upon 
to carry the weight and also any bending strain which may come upon them 
when the truck rounds a corner. The outer bearings are then located between 
the axle shaft and the housing. This generally makes it necessary to pull the 
wheel of the tapered end of the shaft before this bearing can be removed and 
the axle shaft withdrawn. It is, therefore, necessary to remove both the 
wheels and the axle shaft before the differential unit can be taken off for in- 
spection, cleaning, adjustment and repair. 

The term three-quarter floating applies to the axles which are so constructed 
that only one bearing is mounted in the hub of each wheel between one hub 
and the housing and the axle depended upon to maintain the alignment of the 
wheels, that is to keep them from wobbling. The fact that this puts some 
bending strain on the axle shaft distinguishes it from the full floating type. 

Another type of axle, known as the internal drive type has become very 
popular in the last few years, especially for light trucks. This form of axle 
employs a rigid forging like that of a dead axle, on the ends of which the 
wheels are mounted, to support the weight of the truck. The differential is 
bolted to the axle near the center. From the differential run two drive shafts 
on the outer ends of which are mounted spur pinions which mesh with internal 
gears about the size of ordinary brake drums mounted on the hubs of the rear 
wheels. 

When the power is to be applied to all four wheels of the truck instead of 
only two, special axle construction becomes necessary. One method is to apply 
the power to the wheels by the use of internal gear drive. The differential 
housing is mounted above the solid axle forging. The axle shafts are provided 
with universal joints located directly above the steering knuckles so that the 
wheels can be steered. 

Another construction employs a hollow rear axle in which are housed the 
differential and the two axle shafts. The steering knuckles and the ends of 
the axle housing are made larger than usual, and in them are housed the uni- 
versal joints. The short shaft which extends from each universal joint outward 
through the hollow spindle is provided with a flange which serves to drive the 
wheel. The mounting of the wheel on the outside of the hollow spindle with 

CMC 



Chassis — Lecture V 



Page 3 







FIG. NO.l. 



w. 



4 I 1 E2 




Sketch in section illustrating differential. 



CMC 



Chassis — Lecture V Page 4 

= 

the drive through this flange is quite similar to that employed in full floating 
construction. 

If the front wheels only are steered, there should be one differential to 
divide the turning effort equally between the front axle and the rear, and yet 
allow the front wheels to run at slightly lower speed than the rear wheels, as 
they travel a shorter distance when rounding a corner. Each axle would, of 
course, require a differential to permit the application of power to both wheels 
and prevent slipping when rounding a corner. 

If all four wheels are controlled by the steering gear only the differentials 
in the front and rear axles are required as the front and rear wheels track 
when turning. 

From time to time the rear axle should be jacked up and the fit of the rear 
wheel bearing determined by making an effort to wiggle the rim of the wheel. 
While one man attempts to move the wheel, another can place his hand on a 
brake support bracket and the edge of the brake drum, and so easily determine 
the amount of play. 

Spring clips, pins in radius rods and truss rods, and also the brake rods, 
should be inspected carefully, at least once a week. 

The work shaft should be examined for the amount of end play. No ad- 
justment should be attempted by anyone except a skilled mechanic. If the 
driving worm is mounted between two tapered roller bearings the desird play 
may be l/64th of an inch to allow for expansion as the worm becomes warm. 
If a ball thrust bearing, located at one end of the worm is employed, the 
amount of end play may be so little that it cannot be felt. 

Lubrication is probably the most important detail in connection with care of 
the rear axle. 

To insure effective lubrication of the driving gears the differential mechanism 
and rear axle housing should be kept filled to such a depth that the driving 
gear will dip an inch or an inch and one-half in heavy mineral oil, about the 
consistency of molasses (similar to 600-W). This will follow the gears as 
compared with hard grease in which they might cut tracks. Particles of metal 
worn or chipped from the corners of the gear teeth will sink to the bottom of 
this heavy oil whereas with grease they might be carried in suspension into the 
gear teeth and bearings where they would cause noise, wear or even breakage. 

The rear axle housing should never be filled with a lubricant to a greater 
depth than that recommended by the manufacturer in his instruction book 
.(sometimes indicated by high level drain plug). 

The manufacturer generally does not recommend the use of graphite with 
the oil in a worm driven rear axle. 

The drive pinion and internal gear of the internal drive rear axle are in 
most cases lubricated with grease or graphite grease. 

The grease cups and oil cups on various points of the rear axle assembly 
such as on the brake shafts, spring saddles, torsion and radius rods, etc., 
should be filled faithfully. 

When chain drive is employed the chain should be removed every two or 
three weeks and washed in kerosene to remove the grease, dirt and grit. It 
should then be soaked in a hot mixture of tallow and graphite and drained and 
wiped off very carefully. In this way the lubricant gets inside of the rollers 
where it is needed, and to a certain extent the grit is kept out. 

The differential case should be drained, flushed with kerosene and refilled 
every 1000 or 2000 miles, as recommended by the manufacturer. 

CMC 



Chassis— Lecture V P&9 e 5 



As we have just enumerated the several different types of rear constructions, 
it may be well to mention a few of the relatively important repairs. Besides 
having a proper adjustment of the driving pinion, it is very essential that the 
entire moving mechanism is free to turn from either shaft or axle. Generally 
the parts of a differential suffer little or no wear, but should they need re- 
placement, this is accomplished by removing the housing proper, and dis- 
mantling the pinion casing, replacing and assembly. Adjustment in rear 
axles is more or less a matter of shop practice and will be treated in detail in 
the next period. 



c M c 






Chassis — Quiz Questions Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
CHASSIS SECTION 

Quiz Questions 

1. What is the purpose of a clutch? 

2. Name three common types of clutches. 

3. With what material is a con clutch generally faced to give smooth- 
ness of engagement? 

4. What attention does this facing require? 

5. What kind of oil is suitable? 

6. What is meont by "dragging?" 

7. What is the remedy, 

8. What is meant by "grabbing?" 

9. What is done to make the action of a cone clutch smoother? 

10. What is the purpose of the clutch brake? 

11. How far should the clutch pedal be pushed down before this clutch 
brake comes into action? 

12. If no clutch brake is provided, what causes the gears and cone or disc 
to quit spinning when the pedal is held down? 

13. Under what condition is a clutch most liable to slip? 

14. What is the result if it is allowed to slip? 

15. What should be done if a clutch slips badly on high? 

16. What attention does a three-plate clutch need when it slips? 
IT. When it grabs? 

18. If a clutch is made to run in oil and the oil is too stiff, what will be 
the result? 

19. What will be the result if a disc clutch is allowed to slip? 

20. How should the throttle and the clutch pedal be used to allow a smooth 
start with a minimum of wear on the clutch? 

21. What should be done with the clutch and throttle when the rear 
wheels pass over an obstruction high enough or a depression deep enough 
to cause considerable spring deflection? 

22. Why is this necessary? 

23. What will be the result if it is neglected? 

24. What position should the throttle be in when the clutch is held out? 

25. Why? 

26. What is the purpose of a transmission? 

27. How many different ratios are generally provided? 

28. What must be done with the clutch when the gears are to be shifted 
from one speed to another? 

CMC 



Chassis — Quiz Questions Page 2 

29. If the gears make a burring noise or clash when the shift is made, 
what will be the result? 

30. If they are shifted without the clutch being held down or released 
properly, what may result? 

31. What are the three common locations of the gear box? 

32. From what kind of material are the sliding gears made in order that 
they may resist wear? 

33. What happens to the corners of the teeth if they are carelessly or 
unskillfully shifted? 

34. What are the properties of a lubricant suitable for use in a gear box? 

35. How much is needed? 

36. What is the result of overfilling? 

37. What will be the result if a stiff -bodied grease (stiff as cold butter) 
is used in the gear set? 

38. What advantage has graphite mixed with grease? 

39. What is the disadvantage of a low-grade graphite? 

40. State in order each and every operation which the driver should per- 
form in starting the engine and getting the car under way until he is running 
in the highest speed. 

41. When the clutch is engaged in starting from a stand-still in first speed, 
what precautions should be taken to prevent sudden engagement and jerking, 
stalling, or excessive wear on clutch facing? 

42. After the shift from first to second, or from second to third, how 
should the clutch engage? 

43. Should the clutch be engaged first or the throttle opened first? 

44. When the gears are to be shifted into a lower speed, should the clutch 
be pushed clear against the floor board or only far enough to release it? 

45. Why? 

46. Should the throttle be open or closed on this shift? 

47. Why? 

48. Explain the double-pedal motion which a skilled driver uses in shifting 
a truck or car where it is difficult to shift into a lower gear. 

49. Explain how to handle gears when clutch will not release at all. 

50. Explain how to start an engine without a hand crank by means of 
the gears. 

51. Which gears should be used? 

52. If turning is to be done by hand on the rear wheel, what precaution 
should be taken to be safe? 

53. If car is coasting and gears are in first speed, what may be the result 
of sudden engagement of the clutch? 

54. What two types of universal joints are used in vehicles? 

55. What attention do all joints made of metal require? 

56. What attention do the metal housings require to keep them tight? 

57. What attention may leather boots require? 

58. What kind of lubricant will be most satisfactory? 

59. Why? 

CMC 



Chassis — Quiz Questions Page 3 

60. Why are fabric or leather joints seldom used in the main propeller 
or drive shaft when they are used between engine and gear box? 

61. What attention do they receive? 

62. What may there be in connection with them which will require 
lubrication? 

63. What attention will the slip joint in the propeller or drive shaft re- 
quire? 

64. How often? 

65. What are the two types of brakes? 

66. When one set of brakes is used continuously on a long descent what 
harmful effect will result? 

67. Will using the two sets of brakes alternately relieve this effect? 

68. Of what material are brake linings made to enable them to better 
resist heat? 

69. How can brake wear be avoided when a truck or car is descending a 
long, steep grade? 

70. What may be the result of sudden engagement of the clutch when 
the truck or car has been coasting with a set of gears engaged and the clutch 
released? 

71. What precaution should the driver always take before descending a 
hill, especially if it has a turn around which he cannot see? 

72. Is it an easy matter to shift gears from one speed to another when 
the car is moving at a fair rate of speed? 

73. When car is left on a hillside, what precaution should invariably be 
taken to prevent its moving away? 

74. What is meant by a sprag? 

75. When should the sprag be used? 

76. What will be the result of dropping a sprag if the car has begun to 
back up? 

77. When trailers are to be towed up a hill or stopped on a grade, what 
precaution should be taken with the sprags or other devices to prevent them 
from getting away? 

78. Describe the method of operation and advantages and disadvantages 
of check blocks, sprags and ratchets which might be used on trailers? 

79. Are trailers generally equipped with brakes? 

80. Where is the control lever or pedal generally located? 

81. What is the result of violent application of the brakes? 

82. If a car skids or swings to one side when the brakes are set, what is 
probably wrong with the brakes? 

83. When brakes are to be adjusted why is it generally advisable to jack 
up the rear axle? 

84. What is the purpose of a brake equalizer? 

85. Will it insure equalized braking effort on both rear wheels when one 
brake is greasy or improperly adjusted? 

86. When brake adjustment has been made, should the brakes exert any 
drag? 

87. When a truck or car is to descend a slippery or muddy grade or is to 
be stopped on a slippery surface, it is better to hold down the clutch and bring 

CMC 



Chassis — Quiz Questions Page 4 

the car to a stop with the brakes or to retard the motion of the car with the 
brakes while the engine is engaged in one of the lower speeds? 

88. When the rear end of a car skids to one side what should be done 
with the clutch or throttle and which way should the steering wheel be turned 
to end the skid? 

89. If the front wheels of a car or truck fail to control its direction on a 
turn how should they be turned if they must strike a curb? 

90. What is the purpose of a differential? 

91. What special disadvantage may a car suffer when equipped with the 
ordinary type of equalizing differential? 

92. Under such conditions what does the driver generally find necessary 
to do to increase the traction of the wheel which spins? 

93. In the ordinary type of differential, is the turning effect applied to 
one wheel or to both wheels when a car is driven around a corner? 

94. In the so-called non-stall or the overrunning type of differential is 
the power applied to both wheels or to the outside wheel or to the inside wheel 
when the car is driven around a corner? 

95. If such a differential has a large amount of lost motion, what care 
must be taken to avoid damaging the rear system? 

96. When the clutch is engaged suddenly what damage may result? 

97. What is meant by a differential lock? 

98. How is it operated? 

99. What might be the effect when a heavy loaded truck equipped with 
such a differential lock makes a turn on dry pavement with the differential 
locked? 

100. What is meant by a dead axle? 

101. What are the advantages and disadvantages of double side chain 
drive. 

102. What attention do the chains require? 

103. How should they be treated to give the best results? 

104. What are the more common causes of excessive snapping noise in 
chains? 

105. What is meant by a live axle? 

106. What attention do the bevel, worm or spur gears in the middle of 
the rear axle require? 

107. What are the properties of a suitable lubricant? 

108. How much should be used? 

109. If too much lubricant is put into the axle housing, where will it run 
out? 

110. If the required amount of heavy oil has been placed in an axle hous- 
ing and the housing is so tight that it has not leaked out, what should be done 
before an additional supply is poured in? 

111. When power is suddenly applied to the rear axle through a drive 
shaft which is fitted with two universal joints and the wheels try to turn 
foi-ward what does the axle housing try to do? 

112. What is the purpose of a torque or torsion bar? 

113. How is the front end of this torsion bar often supported to cushion 
the shock? 

CMC 



Chassis — Quiz Questions Page 5 

114. How must the spring saddles be secured to the rear axle, if the car 
is fitted with such a torsion bar? 

115. What attention will be required at this point? 

116. What lubricant should be used? 

117. How often? 

118. When the rear wheels turn and drive the car forward how is this 
thrust applied to the frame of the car? 

119. If special radius rods are used, what attention will the joints at 
both ends require? 

120. How often will they require attention? 

121. What attention should the spring clips receive? 

122. How often? 

123. If the spring clips are allowed to work loose and the car employs 
Hotchkiss drive, that is, has no radius or torque rods what may happen to the 
spring center bolt? 

124. What would be the best lubricant for universal joints which are 
fitted with tight housings? 

125. How often should they receive this attention? 

126. What provision is made to retain the lubricant? 

127. If the housing is made of metal, what adjustment may be required 
to take up the wear in the packing? 

128. What would be the best lubricant for spring shackles which are 
fitted with compression cups? 

129. When oil wells or oil cups are provided what kind of oil is generally 
used? 

130. Mention briefly the advantages and disadvantages of wood wheels 
as compared with metal wheels. 

131. On the five following types, wood, wire, pressed steel, disc, and cast 
steel, which would be especially suited for use on a heavy truck? 

132. On a light touring car for officers' use or an ambulance? 

133. When the treads of front tires show excessive wear or steering is 
unusually difficult, what may be wi'ong with the front wheels? 

134. Should the front wheels be closer together at the ground or at the 
top? 

135. At the front or at the back? 

136. How much? 

137. What is the purpose of the gather? 

138. If a front wheel turns out of true or seems to have too much play, 
should this condition be allowed to remain? 

139. Why? 

140. Which would be more suitable for carrying heavy loads found in 
trucks, ball bearings or roller bearings? 

141. In what shape are roller bearings for wheels generally made to with- 
stand the end pressure which they receive when a heavy truck turns a corner? 

142. What provision is there generally made in the hub in order to keep 
grease in and to keep water, sand and dust out? 

143. If the driver feels sure that mud and sand have worked into a wheel 
bearing, what attention should it be given? 

CMC 



Chassis — Quiz Questions Page 6 

144. When a wheel is mounted by a driver or by a repair man, how can 
it be determined whether the bearings are too tight or too loose? 

145. What will be the result of running with the bearings too tight? 

146. If a cone or cup ball bearing, like those used in a Ford car show signs 
of looseness, which part of the bearing will generally be the first to show the 
wear? 

147. When a cone is grooved or pitted, what should be done with it? 

148. Is it advisable to replace one ball or roller in an old bearing with a 
new one? 

149. Why? 

150. Where should the hand be placed to determine whether motion is in 
the wheel bearings or in the spindle bushings when a front wheel is found to 
have play or lost motion? 

151. How should the hub cap be used by the driver to grease front wheel 
bearings without disturbing the bearing adjustment? 

152. What effect does overloading have on a solid tire? 

153. Overspeeding? 

154. Striking or passing over an obstruction at a high rate of speed? 

155. Running with chains on hard-surfaced roads when chains are not 
necessary? 

156. What two methods are used to secure heavy solid rubber truck tires 
to the wheels? 

157. What effect does a wheel which runs out of true have upon a tire? 

158. What effect will be noted on the front tires, if the front wheels are 
out of alignment? 

159. What is the effect of oil or grease on the rubber of a tire? 

160. What is the effect of turning corners at too high rate of speed? 

161. What is the effect of a violent use of the brakes? 

162. How does the frame of a heavy motor truck differ from the frame of 
a car in material and in shape? 

163. What is the purpose of truss rods beneath the frame? 

164. What attention may the truss rod need from time to time? 

165. How are the parts of a frame fastened together and what will be 
the indications of looseness in these joints? 

166. At how many points may an engine be attached to the frame? 

167. What are the advantages of a 3-point suspension? 

168. What is meant by the term sub-frame? 

169. What attention will be received at the points where an engine or 
gear box is attached to the frame? 

170. Name the types of springs used on trucks. 

171. What attention is required at these points? 

172. How often? 

173. How are springs secured to the axle? 

174. What attention do these fasteners or clips require? 

175. How often? 

176. What is the result of running with the nuts on the clips loose? 

CMC 



Chassis — Quiz Questions Page 7 

177. How are the leaves of a spring held together? 

178. Are the leaves weakened by the fastening? 

179. If clips are allowed to remain loose what may happen to the center 
bolt? 

180. Will this have any effect on front axle location and on steering? 

181. What precaution is made on springs to prevent the leaves from being 
pulled apart? 

182. What device is attached to a spring to prevent the leaves from being 
pulled apart on the rebound? 

183. What is the purpose of rubber blocks? 
•184. Where are they generally placed? 

185. What attention should the leaves of a spring receive? 

186. What is the best material to use on the leaves of a spring? 

187. How should it be applied? 

188. What attention should the springs be given to prevent breakage at 
the center bolt? 

189. How often should this attention be given? 

190. What attention is required at the spot where the bolts go through 
the spring eyes? 

191. How often? 

192. If lubrication of the spring bolts has been neglected or the oil cups 
or grease cups have been broken or oil passages stopped up, what attention 
will probably be required? 

193. What is the result of excessive end play of the spring eye on the bolt 
which passes through it? 

194. Why are the steering knuckles on a front axle set as close to the 
wheels as possible? 

195. If the front axle on a truck were built like that of a wagon, what 
would happen to the steering mechanism when one wheel strikes an ob- 
struction? 

196. What attention is required at the point where the steering knuckle 
turns? 

197. How often? 

198. Should a truck or car be operated when there is an excessive amount 
of lost motion in steering knuckle pins or in steering connections? 

199. If the front wheels have too much gather (are too much cross-eyed) 
or are spread (wall eyed) what can be done to the rod which joins the arms 
on the steering knuckles? 

200. Name all of the parts of the front axle and steering gear which 
require lubrication. 

201. How often should they be lubricated? 

202. What provision is made to keep sand, dust and water out of the 
joints in a tie-rod and steering rod ends? 

203. How often should all steering connections be inspected for lost 
motion? 

204. Why are the front wheels set closer at the bottom? 

205. Why are they set closer at the front? 

CMC 



Chassis — Quiz Questions Page 8 



206. How much closer at the front? 

207. What two types of mechanism are used in the lower part of the 
steering gear? 

208. If either type of mechanism is made absolutely irreversible what 
may happen to some of the steering mechanism when a car slides into a rut 
against a curb at a slight angle? 

209. What attention does the base or chuck of a steering gear require? 

210. What two parts of motor truck mechanism are most essential to 
safety? 

211. When there is a really excessive amount of lost motion in the steer- 
ing mechanism and a clicking or knock can be heard as the wheel is turned 
rapidly back and forth for a short distance, where are adjustments liable to 
be necessary? 

212. Name all parts of the entire mechanism which require lubrication? 

213. How often do they require lubrication? 

214. Name the lubricant for each place. 



CMC 



Engine — Lecture I Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course- 
ENGINE SECTION 

LECTURE I 

Principles of the Gas Engine 

As a foreword I may say that during this lecture I will make comparisons 
to things that are common in life so you may comprehend the details that I am 
about to explain. For example, if I were lecturing on paint mills instead of 
motor cars and were to say that the grinding member of the mill was sup- 
ported by a Chrome Steel Shaft, the tensile strength being 250,000 lbs. per 
square inch, and that the grinding member proper had a crushing capacity of 
70 tons, and that it required 30 indicated horse power to operate the same, 
it would be rather difficult for you to become interested or, I should say, it 
would be impossible to follow my lecture in an intelligent way, but if I were 
to tell you that the paint mill is practically the same in construction as the 
coffee mill, a fair idea of the principle would be conveyed to you. So I will 
endeavor to make at intervals such omparisons as will enable the layman to 
grasp the underlying principle of every unit I may be explaining at the time. 

Owing to the fact that the motor car has practically succeeded the horse 
drawn vehicle, we can start right there with a very favorable comparison. 
After carefully analyzing the situation, we find that the horse furnishes the 
motive power, and can be likened to the motor. The harness too, for the fact 
that it conveys or connects the motive power to the wagon, will answer for the 
transmission because, in reality, if it were not for the harness the horse would 
simply walk away from the rig. The reins can be likened to the control for if 
we wish to go to the right we simply pull the right rein while in the motor 
car we simply turn the wheel to the right. The rest of the wagon such as 
body and wheels remain unchanged excepting for more substantial construction. 
Owing to the fact that the rear wheels of the motor car are permanently fast- 
ened to the outer ends of the axles, when we turn the corner, an equalizing 
gear must be provided to permit the off or outer wheel to cover more ground, 
as when soldiers column right, in turning the corner, the pivot man marks time 
while the other man takes a longer step. This briefly outlines the functions of 
the important units connected with the motor car, the running gear, power 
plant, transmission of power and the method of control. We will study each 
unit with its essential auxiliaries, independently. 

We will start with the power plant. Everyone of you at some time during 
your past has had the opportunity to see or possibly operate the old fashioned 
grindstone in which the power is applied with the foot by means of a foot 
treadle, and with a few necessary parts, reciprocating motion is converted into 
rotary motion. Let us draw a sketch of this outfit on the blackboard (Plate 
No. 1). We have the stone which is made heavy enough to overcome the up- 
stroke of the foot treadle, as the upstroke is not the power stroke. The grind- 
stone is supported on an axle or a shaft mounted in bearings. At the end of 
the axle or shaft and at right angles to it is a small arm which is called a ci-ank. 

CMC 



Engine — Lecture I 



Page 2 



Hence we have the familiar term, crankshaft. The next step in the construc- 
tion is the rod which connects the point of power application to the crank- 
shaft. This is known as the connecting rod, which incidentally, is simple 
enough because, as its name implies, it simply connects two points. The speed 
of the stone depends upon the power applied at the treadle. Hence the con- 
version — reciprocating into rotary motion. For convenience, we will invert 
the blackboard and eliminate the frame and foot power attachment (Plate 
No. 2). Our next procedure will be to- construct the labor saving method of 
power application to the connecting rod and incidentally accomplish our needs. 
Leaving the grindstone for a minute let us imagine we have an ordinary muzzle 
loading cannon. The first thing we have to do is to place the charge of powder 
in the cannon. Then we bring out the old familiar ram rod and compress the 

PLATE NO. 1. LECTURE NO. 1. 




Arrow A indicates where power is applied, the motion being reciprocating. 
Arrow B indicates the'conversion into rotary motion, also the direction of the 
wheel. 

charge by ramming it into the breech. At this point, we have explained two 
functions, one being charging and the other being compressing. For con- 
venience, we will place the cannon on the blackboard in such a position as 
will permit us to utilize the power of the explosion (Plate No. 3). A cast iron 
trunk or piston is placed on the upper end of the connecting rod so as to retain 
as much power as possible. Assuming ignition now to take place and allowing 
that the charge is not too heavy, the piston would be blown to the lower end of 



CMC 



Engine — Lecture I 



Page 3 



the cannon or the end of its stroke. The grindstone which is now assuming 
the role of a flywheel, stores up enough energy to bring the piston back and 
in doing so exhausts the burnt charge providing that means were allowed for 
the exhaust. It is apparent from the foregoing talk that to convert reciprocat- 
ing motion into rotary motion, there are four individual functions performed 
in the gasoline engine. One is the admission of the charge, the second one 
being compression, the third function being ignition or the power stroke, and 
the fourth is the exhaust. Hence the four cycle engine. 

PLATE NO. 2. LECTURE NO. 1. 




Inverted grindstone minus frame and treadle. 

It will be well for us to memorize the nomenclature of the parts just men- 
tioned. Starting with the Balance or Fly Wheel, we have the Shaft which 
supports it. As I previously mentioned this Shaft is called the Crankshaft, 
and is mounted in the Main Bearings. To the Crank Pin is fastened the lower 
end of the Connecting Rod. The Connecting Rod whose function is to connect 
the Piston to the Crankshaft, at the upper end is, by means of the Piston Pin, 
fastened to the Piston. The Piston reciprocates in the cylinder. 

As you no doubt are familiar with the fact that we have four, six, eight and 
twelve cylinder motors, I may add that for every cylinder there is an extra 
crank on the crankshaft, and likewise a complete piston assembly with all of 
its auxiliaries is required. 



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Engine — Lecture I 



Page 4 



PLATE NO. 3. LECTURE NO. 1. 



Piston rings 



Piston 



Balance or fly wheel 



Wrist pin 




on or cylinder 



Connecting rod 



Crankshaft 



Utilizing the power of the cannon to convert reciprocating into rotary motion. 



CMC 



Engine — Lecture I Page 5 

Note to Instructor. — Answer all questions excepting those pertaining to 
valve or piston construction. 

A single cylinder engine is not suitable for driving a motor truck or car be- 
cause there are three idle strokes for each working stroke of the piston. The 
engine would pull the machine with a series of jerks. By having four cylin- 
ders so arranged that the explosions are equally spaced, a very much more 
satisfactory pulling effort is obtained. For passenger carrying cars as many 
as 6, 8 and 12 cylinders are used to get smoother pull, but the fuel consumption 
is greater with the increased number of cylinders. The four cylinder engine 
is the most satisfactory for a truck or light car. 

Connecting rods are made of steel forgings. The upper connecting rod bear- 
ing is usually a bushing of hard bronze forced into the boss at the end of the 
connecting rod. It bears on and runs in connection with the wrist pin which 
passes through it, the wrist pin being case hardened steel. A connecting rod 
is usually equal to 2.5 times the length of the stroke. Long stroke motors 
have longer connecting rods than short stroke motors. The lower end of the 
connecting rod has a lining or bushing of Babbitt or white metal where it fits 
the crank pin. On light, low priced engines the Babbitt metal is often poured 
directly into the rod end and rod cap. On higher priced cars the bushings or 
linings are generally removable. They may be die cast to the exact size and 
form. The better construction is where the bushings are bronze shells lined 
with a layer of high grade Babbitt not over 1/16" thick. 

As has already been mentioned, the upper end of the connecting rod is at- 
tached to the piston by means of a case hardened steel wrist pin. There are 
two general methods employed in attaching these two units. The connecting 
rod is sometimes clamped to the wrist pin and allows the wrist pin to oscillate 
within the bosses of the piston, which are usually lined with bronze bushings 
pressed into the piston. This type is known as an "oscillating" wrist pin. 
The other type is known as the "stationary" type; the wrist pin being securely 
held in position within the piston bosses by means of a set screw or other suit- 
able device, and the oscillating motion occurs between the wrist pin and the 
connecting rod upper bearing, which is also usually a bronze bushing pressed 
into place. 

Excessive wear makes it necessary to replace the piston pin and piston pin 
bearing. Renewing of the bushings only is often insufficient as the pin is 
generally worn also. A shoulder on the pin can generally be felt or the wear 
can be detected by measuring the pin with a micrometer caliper. As a rule 
the connecting rod bearings and the wrist pin bearing wear more than the 
main engine bearings and should be examined first. 

Difficulty is sometimes experienced in removing piston or wrist pins. This 
can many times be accomplished by turning down a rod that will slide freely 
through the bushing and then threading it. Over this is fitted a bushing 
slightly smaller than the hole in the piston. If the rod threaded is a standard 
S.A.E. thread, a standard nut may be used, and by screwing the nut down on 
the rod the pin may be drawn out. If the piston is aluminum a wrist pin which 
seems tight can be loosened by plunging the piston into boiling water, after 
first having removed the locking device. 

Removing piston pin bushings, if they are of the oscillating type, can be 
accomplished by the same process as mentioned in the removing of wrist pins. 
A reamer may also be used and the bushing reamed out, if the idea is to renew 
the bushing. If the bushing is slotted carefully with a hack saw while the pis- 
ton is held in a vise it will be easy to drive out. 

CMC 



Engine — Lecture I Page 6 

Removing the bushing in the upper end of the connecting rod is sometimes 
a difficult task. This can be successfully accomplished in several ways, the 
most common of which is to open the jaws of a vise far enough so that the end 
of the connecting rod rests upon the jaws and at the same time gives sufficient 
clearance for the bushing between as it is driven out. A bar of brass or steel 
of suitable diameter is used to drive the bushing out. 

Another way to remove a connecting rod bushing is to open the jaws of the 
vise wide enough to admit a piece of pipe slightly longer and larger than the 
bushing to be removed. The jaws should be opened wide enough to admit fur- 
ther the end of the connecting rod, and a steel bar, in size the diameter of the 
hole in the connecting rod and slightly longer than the bushing to be removed. 
By simply tightening the vise the bushing is forced out by the steel bar into 
the pipe. 

Lower connecting rod bushings or bearings will be treated under the subject 
of "Motor Bearings." 

The crankshaft is a solid, one-piece steel forging. The pins and journals 
are turned to approximately the correct size with a lathe and are finished in a 
grinder to correct size within one thousandth of an inch. 

If one side of the crankshaft is heavier than the other side there will be 
some vibration when the engine runs at high speed, although the shaft may 
be in stag balance, that is, may not appear heavier on one side than on the 
other when placed on a pair of parallel knife edges or on a pair of ball bear- 
ings. It may tend to whip out of line slightly, when run at high speed. Each 
crank pin on the crankshaft tends to pull harder in its own direction, exerts 
heavier pressure on the bearings, and tends to pull the shaft more out of line 
as the speed of the engine increases. This tendency is offset in some engines by 
the use of counter-balances or counter-weights which are bolted or electrically 
welded to the crankshaft. For the engine on a car or light truck, there is so 
little trouble experienced with crankshaft vibration or with bearing wear, 
that counter-balances are considered unnecessary. 

The purpose of the crankshaft is to change the reciprocating motion of the 
piston to the rotary motion of the shaft and flywheel. 

There is practically nothing in connection with the care of the crankshaft 
except to keep it properly lubricated and to keep the bearings properly taken 
up. The subject of lubrication and bearing fitting is taken up under a separate 
heading. 

There are few repairs to the crankshaft which the ordinary mechanic can 
accomplish. When the engine has been taken down, the crankshaft can be 
measured with micrometer calipers to determine whether any of the pins or 
journals are worn out of round. A shaft which is worn undersized or out of 
round can, in the base repair unit, be put in the grinder, all the pins and jour- 
nals trued up to within ten-thousandths undersized or twenty-thousandths 
undersized, and new Babbitt can be fitted to the engine base, or rod and bearing 
out of line reamed to fit the shaft. This will be explanied later. 

Sometimes the welding of the crankshaft is attempted. In most cases the 
attempt proves unsuccessful because the metal on both sides of the weld is 
weakened by being burned and it is almost impossible to weld a shaft so that 
it will be true without having a light cut taken off of each bearing. If the 
crank is bent or sprung slightly in service it may not be visible to the eye except 
when the shaft is revolving between centers on a lathe with a tool or other 
object held stationary close to the center bearing. If it is only slightly out of 
true, proper fitting of the bearing is almost impossible. 

CMC 



Engine— Lecture I Page 7 

A shaft is sometimes straightened between centers in a heavy engine lathe 
or by being supported by its ends between suitable blocks under an arbor press. 
It is even possible to -improvise a straightening process with timbers or a heavy 
automobile jack. Assuming that the shaft is bent, if it be sprung in the oppo- 
site direction with a bar and while held in that position the center main bear- 
ing is struck a sharp blow with a hammer, the bearing surface being first 
protected by a piece of brass or other available metal, the tendency of the shaft 
will be to assume its original alignment. This operation should not be at- 
tempted except in a heavy engine lathe. A suitable block should be procured 
upon which leverage may be obtained in using the bar. This operation is re- 
peated again and again, a test being made each time the shaft is sprung. In 
making these tests one should not be misled by a bearing surface of the shaft 
that is probably worn out of round ; the test should be made at the side of the 
bearing where little or no wear is liable to take place. And even then it is not 
the best thing for the lathe. In the base plant, if the shaft is bent very badly, 
it would be turned down to one of several accepted, undersized dimensions. 

It is generally a long and tedious job, depending greatly upon chance and 
the ability of the operator of the bar, to guess the proper amount of pressure 
to apply and the proper place to apply it. Where there is a machine shop in 
connection with the auto repair shop, the straightening of bent crankshafts 
would come under its routine work. 

The crankcase may be used as fixture for testing the alignment of the main 
bearings of the crankshaft with little difficulty. The case is placed on the 
bench and a strip of pasteboard about l/64th of an inch thick placed beneath 
the front and rear bearings of the crankshaft. By these the shaft is raised 
from the center bearing and side play prevented. A pointer is then clamped 
on the side of the case at the center bearing, and by turning the shaft the 
amount it is out of true is determined. This method is quicker than testing 
in a lathe and can be used to advantage when without machine shop facilities. 

A scored crankshaft. When the engine has been disassembled the crank- 
shaft should be examined. If any rings or ridges can be seen or felt, the 
crankshaft should be held in a vise between grooved wooden blocks and care- 
fully "emery clothed." To do this properly some fine emery cloth should be 
torn into strips about 1%" wide and well oiled and the crank rubber. Emery 
tape is better for this work when obtainable. If the emery cloth completely 
encircles the shaft, and a long steady movement be imparted to it, there will 
be no tendency to make the shaft oval. 

It may be found that a crank pin is not only scored, but on testing it with 
calipers, is found out of true, i. e., not perfectly circular. The usual and best 
plan is to have the shaft ground true on a special grinder, but this may not 
always be possible, owing to the lack of facilities. 

The best alternative is to first file the untrue parts of the shaft with a very 
smooth file to as accurate a circular shape as is possible, testing frequently 
with calipers. A lead "lap" is then made in a set of clamps or an old rod and 
bored out to size to fit the crank pin. Paper or card shims are inserted be- 
tween the two halves of the "lap" so that the halves can be gradually closed 
down by the bolts onto the crankshaft. The "lap" is dressed with fine emery 
and oil and worked around the crank pin by hand until a good surface is 
obtained. 

The flywheel of an internal combustion engine is made of cast iron or semi- 
steel. Some manufacturers of high speed motors encircle the flywheel with a 
steel band to eliminate the possibility of it "throwing" to pieces at high speed 
due to centrifugal force. 

CMC 



Engine — Lecture I Page 8 

In an automobile engine the pressure that operates from the combustion 
acts only on one side of the piston forcing it to slide only one way. After be- 
ing forced downward, the piston must be brought upward again and this is 
done by the flywheel, which is attached to the end of the crankshaft. When 
once started the flywheel continues to revolve until friction or some other 
resistance stops it; but before this can happen the pressure is again exerted, 
keeping it going. The flywheel being attached to the crankshaft, they revolve 
together, and because the piston is conncted to the crankshaft by the connect- 
ing rod, it moves with them. The piston moves downward by pressure, starts 
the crankshaft and flywheel, and then the flywheel in continuing to revolve, 
moves the crankshaft and piston. 

The fitting of the crankshaft to the flywheel. It is essential that the flange 
of the crankshaft and the depression in the flywheel to receive it be machined 
to fit perfectly. If there is any variation in these two diameters, the bolts 
which hold these two units together will soon loosen and a pound or knock will 
result. The proper machining is taken care of by the manufacturer and it 
is seldom that this condition arises. However, such a knock sounds very much 
the same as the pound of a crankshaft main bearing. 

Cutting teeth around the outside diameter of the flywheel into which the 
pinion of the electrical starting device may mesh, has become a popular prac- 
tice among manufacturers using electrical starting equipment. Sometimes the 
teeth are cut into the large ring gear which is bolted to the flywheel. 

On nearly all automobile engine flywheels, markings will appear on the 
circumference surface of the flywheel, which indicate the position the crank- 
shaft is to be placed for correct setting of the valves. These markings are 
different on nearly every make of car and the manufacturer's instructions 
pertaining to them must be followed. 



CMC 



Engine — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
ENGINE SECTION 

LECTURE II 

Cylinders and Valves 

In our last lecture we outlined the fundamental principles of the four stroke, 
internal combustion engine. If you will remember, it was first necessary to 
admit the charge. This was accomplished through the admission or inlet 
valve. The charge was then compressed, ignited, and on the last stroke of the 
piston it was exhausted through the exhaust port or valve. There are several 
types of valves used in engine construction, but the one which is universal, 
or I should say used the most, is the 45 degree type. We will now sketch on 
the blackboard a cylinder head showing the position of the cams when the 
valves are closed. The both valves are securely seated by means of a spring 
and their operation is as follows: 

Assuming that the piston is at the top of the power stroke, which is the point 
of ignition, and combustion takes place, the piston is driven down by the 
expansion of the gases to a point which is approximately seven-eighths of the 
entire stroke, in terms of degrees, varies from 30 to 45 before bottom center. 
The cam for lfting the valve is so timed that it permits it to open at this 
point. It can be seen from the sketch that the cam is so cut as to allow the 
valve to remain open until the piston has returned to the top of the exhaust 
stroke. At this point it closes and we are now ready to take in a fresh charge. 
It will be well for us to acquaint ourselves with the nomenclature of this par- 
ticular mechanism. Starting with the valve which is known as the poppet 
type we next have the valve guide bushing, when placed in the cylinder the 
valve is surrounded by the valve spring which is held in position by the valve 
spring spool and key. Next we have the valve lifter sometimes called the 
plunger or tappet which is incased in the valve plunger guide. The lower end 
is generally a flat hardened surface or there is provided a small roller which 
permits an easy action of the tappet. At the valve stem end of the tappet, 
means are provided for adjustment or what is commonly known as clearance. 
This distance or clearance is usually from eight to twelve thousandths of an 
inch, which can be measured by a thickness gauge or judged by a few cigarette 
papers. 

Referring to Plate No. 2, we find expressed in degrees, which is usually 
marked on the flywheel, the time of valve opening and closing. Referring to 
Figure No. 1, the inlet valve has a lag of eight degrees in opening. That is to 
say that if the flywheel were divided in 360 degrees and, assuming the piston 
to be on top center, the inlet valve would not open until eight degrees after 
top center. 

The piston is now on the down or suction stroke and the charge is drawn 
into the cylinder when the piston is 38 degrees past bottom center, the inlet 
valve closes, and compression starts. It is well to note that, of the 360 degrees, 
210 degrees are consumed in suction. 

CMC 



Engine — Lecture II 



Page 2 



PLATE NO. 1. LECTURE NO. 2. 




Intake 



Showing valve assembly and its relation to cam and crankshafts 



Note to Teacher: The water jackets are eliminated to facilitate instruction 
and avoid confusion. 



CMC 



Engine — Lecture II 



Page 3 



PLATE NO. 2. LECTURE NO. 2. 

T. C. 

Inlet opens 



Intake closes 



Intake closes 




FIG. 2. Compression Stroke, 



CMC 



Engine — Lecture II 



Page 4 



PLATE NO. 3. LECTURE NO. 2. 



Exhaust opens 




FIG. 4. Exhkust 



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Engine — Lecture II Page 5 

In the next figure we find that as soon as the intake closes, compression 
starts, and until the piston returns to top center, which is the point of igni- 
tion, the charge is compressed to what is termed the compression pressure. 
This consumes 142 degrees more, or in other words, completes the first revo- 
lution excepting the 8 degrees lag of the inlet valve. 

The next stroke is the power stroke, which generally is the most effective 
up to about 46 degrees before bottom center, and in the last figure, the balance 
of the revolution is used in exhaust. Notice at this time, the greatest part 
of any one revolution is used in exhausting the spent charge. 

The above is known as timing the valves, and the shop study will clear up 
any dark corners in your minds. 

Troubles and remedies will also be treated in detail during shop periods. 

A common mistake is an attempt to seat a badly grooved or pitted valve on 
an equally bad seat, which is an almost hopeless job. It is also useless to use 
coarse emery and bear down with all one's weight on the grinding tools with a 
hope of quickly wearing away the rough surface. The use of improper abrasive 
material is a fertile cause of failure to obtain a satisfactory seat. Valve 
grinding is not a difficult operation if certain precautions are taken before un- 
dertaking the work. The most important of these is to ascertain if the valve 
head or seat is badly scored or pitted. If such is found to be the case no ordi- 
nary amount of grinding will serve to restore the surfaces. In this event the 
best thing to do is to remove the valve from its seat and to smooth down both 
the valve head and the seat before an attempt is made to fit them together by 
grinding. It is sometimes necessary to have this work done in the machine 
shop or with special tools designed for the purpose. Another important pre- 
caution is to make sure that the head is not warped out of shape or loose on 
the stem. 

Valves need grinding when either the inlet or exhaust valves leak. The 
exhaust valve has a tendency to leak more than an inlet valve because it is 
exposed to more heat. 

Weak compression generally indicates that the valves are leaking and need 
to be ground, although a lack of compression may result from leaky or worn 
piston rings. If the engine has been torn down so that the valves are acces- 
sible, a test may be made of them by placing Prussian blue on the face of the 
valve. Then turn the valve one quarter around in the valve seat. If the seat 
shows a clear clean line of blue it is a perfect valve. If there are points where the 
blue does not touch it indicates a worn or warped valve and should be ground. 
To test the valve seat it is merely necessary to reverse the operation, placing 
the blue upon the seat and revolving the valve head. 

It may be necessary in grinding the valves to remove the intake pipe. Re- 
move the valve cover plates and valve cap. If the motor has a removable cyl- 
inder head the valves are exposed and are ground into the cylinder casting. 
The valve springs must be removed and this is accomplished with a valve lifter, 
care being taken that mashed fingers are not one result of this operation. 
After the tension is taken from the valve retainer the locking device may be 
removed and the spring taken out, allowing the valve to be lifted from its seat 
and guide. Grinding compounds are made in three grades, coarse, medium and 
fine. The coarse is usually used first, being placed on the valve head and 
equally distributed over the valve seating surface. A light spring should be 
placed under the valve, which will allow the valve to raise from its seat when 
the weight is taken off of it. The valve is then placed in the valve seat and is, 
of course, held in place by the valve stem within the guide. A screw driver 

CMC 



Engine — Lecture 11 Page 6 

or valve grinding tool is used and the valve should be turned about a quarter 
revolution, back and forth in its seat, occasionally lifting it from the seat and 
shifting it around. Do not turn round and round. When the pits on the valve 
are almost removed continue with a finer grinding compound until a perfect 
seat is obtained. Remove the valve and clean all of the grinding compound 
from the head and seat, being sure that none of it has worked down to the 
valve stem into the valve guide. Exceeding care should be taken in cleaning 
away all of the grinding compound. Too much pressure placed upon the valve 
grinding tool will cause rings to be cut in the valve or seat. Pressure of 3% 
lbs. recommended as sufficient. Tests for a perfect valve seat can be made 
with Prussian blue as previously described. A valve that is properly seated 
will bounce back when dropped into its seat. If it stops with a dull thud, either 
the grinding is not perfect or the valve stem is bent. A test for a perfect 
seat can also be made by marking the valve head with pencil marks, placed 
about 1 /4" apart, and if it is possible to wipe all of these marks away by turn- 
ing the valve in its seat, a gas tight valve is assured. 

In grinding the "cage type" valves the same general method is employed as 
in grinding the "poppet type" in an "L" or overhead motor. The cage is 
removed, retained in a suitable retainer and the valve ground in the cage. 

The angularity of a valve seat should never be less than 45° from the per- 
pendicular. Less than 45° will usually produce a sticking valve. 



CMC 



Engine — Lecture III Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ENGINE SECTION 

LECTURE III 

Compression 

You are by this time familiar with the duties of the piston, and in refresh- 
ing your memory you will recollect that its first function was the down or 
admission stroke. In this operation it is very essential that the piston, by 
reason of its duty, must fit the cylinder in which it reciprocates very snugly. 
It is, therefore, provided with several packing rings, the ring being so con- 
structed as to be continuously pressing against the sides or walls of the cylin- 
der. I will draw on the blackboard an exaggerated sketch of the ring show- 
ing how it is split to enable one to place it over the head of the piston. The 
piston is so grooved as to retain this ring, the diameter of which, when closed, 
is slightly greater than the diameter of the piston, the object of this being 
that the high temperature of combustion causes the piston to expand and if it 
were the same diameter as the cylinder, the piston would seize, causing con- 
siderable damage. 

In the cross-section of the drawing on the board we will note that means 
are provided for fastening the piston to the connecting rod by means of a 
piston pin commonly called wrist pin, the general trend being to have the pin 
permanently fastened in the connecting rod. The reason for this is, as will 
be seen in the sketch, that a greater bearing surface can be maintained. 

When new rings are to be fitted in an engine the first operation is to see 
that the slot is closed when the ring itself is placed in the cylinder without 
the piston. Should this space be too great the ring is called undersized and is 
discarded for another. Should it occur that the ring does not close, a flat mill- 
file is used to widen the slot until the ring fits the cylinder without a gap. I 
will pass this sleeve among you which has three rings in it and you will readily 
note the ring which is correct. The next fitting operation is accomplished 
with the piston. This consists of placing the ring in the groove so that there 
is a snug fit all around. The fitting of the rings being very important, it will 
be well to note that both of these operations must be executed with care. After 
having fitted the rings to the cylinder and then to the piston we enter into the 
third and last operation called "lapping in." This is accomplished by placing 
the connecting rods in the piston, inserting the pin and fastening same. A 
piece of wood, say two or three feet long,, is next placed through the lower 
bearing of the rod. The grinding element or compound is applied in small 
quantities around the rings and the entire assembly is placed in the cylinder 
which is fastened in a horizontal position on the bench. The mechanic now 
substitutes himself as a crankshaft and by continuously pushing and pulling 
the piston up and down in the cylinder for an hour or more, a perfect bearing 
of all the rings upon the walls is developed. It is advisable to place a block 
of wood in the head of the cylinder before inserting the piston for this reason, 
(referring to the blackboard), when a cylinder is bored it is not finished any 

CMC 



Engine — Lecture III 



Page 2 



PLATE NO. 1. LECTURE NO. 3. 



Piston Or Wrist Pin 




Section of Piston 



wttUHtitttytttAfc 



W 



Yfrnm 



77m 



vzzz. 



r 77777l 




-w 



Piston Ring 



T 




Note to Teacher : Any parts that may seem confusing to the student should 
always be drawn on the blackboard in perspective. This however is unneces- 
sary if the actual parts are on hand. 



CMC 



Engine — Lecture III Page 3 

further than the end of its stroke. You will readily see that should the piston 
be placed in without this block, it would pass into the firing chamber where 
the top ring would be permitted to expand preventing the pulling out of the 
piston. This has caused much loss of time as the ring generally must be 
broken before the piston can be relieved. In placing the cylinder on the piston 
when a motor is being assembled, the rings are so arranged that the slots 
are equidistant. Every available detail such I just mentioned is guarded 
against as any one may in time, cause loss of compression. In conclusion, 
when a piston is of the proper diameter, and the rings fit perfectly, they will 
only permit sufficient oil for lubricating purposes to pass. It will be seen from 
this that if the rings fit perfectly and are not in line, carbonization will be 
almost eliminated. 



CMC 



Engine— Lecture IV Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ENGINE SECTION 

LECTURE IV 

Bearings 

In this lecture, for convenience, we will deal with a one-cylinder engine. As 
you will remember, the crankshaft of the grindstone, supported the stone and, 
in this case, supports the flywheel. We also stated that one end of the shaft 
there was located, at right angles to the shaft, an arm or crank, and from this 
we deduce the name crankshaft. (Fig. 1, Plate I). Now then, the bearings 
that support this shaft are known as the crankshaft or main bearings. They 
are usually in two parts and made of bronze, or white metal Babbitt, or other 
metal that does not wear rapidly. As shown in Fig. 2, the bearings are split 
lengthwise, one part being supported by the engine base so that the shaft lies 
in it and the other part covers the shaft at the same point and is held in place 
by means of studs. Let us assume that this bearing, through the duties it per- 
forms, has worn so as to require adjusting, Fig. 3 being an exaggerated sketch 
as to how it would appear. The bearing already being in halves, it would be a 
very easy operation to file or machine off, say, one-sixteenth of an inch on 
each side (Fig. 4). This, as is very plain, would permit the bearings to close 
in on the shaft, and when the nuts were drawn up tight it would cease to be a 
bearing. It would be converted into a clamp. At this point it will be well for 
us with the aid of some Prussian blue to determine how well the bearing fits 
against the shaft. I have prepared for you a bearing and shaft upon which 
we will put a very small quantity of bluing; next we tighten the bearing cap 
so as to permit the turning of the shaft. Upon removing the shaft we find that 
a series of marks are transferred to the bearing and incidentally, they indicate 
the true fit of the same. Please pass this around as quickly as possible. I 
may mention here that in scraping the bearing these are the marks that the 
scraper removed, and great care is exercised so as not to allow the scraper to 
chatter or dig, which will remove too much of the metal. After the bearing 
is fitted or rather scraped, the next step is to fill up the space that we so reck- 
lessly filed off. Referring to Fig. 5, we have what is known as the shim, and, 
as you will note, they conform to the outlines of the bearing cap. They vary 
in thickness from a few thousandths to a thirty-secondth of an inch. Now we 
wi 1 ] continue to fill up this space, (Fig. 4). We find that it requires a number 
of these shims to do this and we continue to place them there until we are 
just able to turn the shaft. This operation is called "setting up" and is very 
important for if the shaft is too tight the oil cannot lubricate the bearing 
and it will burn out. On the other hand, if it is too loose it will cause a pound 
when the motor is running. We have found that if this bearing should wear 
a little bit, all that would be necessary would be to take off the lower half 
of the bearing, remove a thin shim from each side, and lock up the cap again. 
Therefore, most bearings are shimmed, and these bearings are called plain 
bearings. The other types of bearings sometimes used on crankshafts are 

CMC 



Engine — Lecture IV 



Page 2 



PLATE NO. 1. LECTURE NO. 4. 
The Crankshaft. 




FIG. NO.l. 



PLATE NO. 2. LECTURE NO. 4. 



Bearing Cap Studs 



Shims 




Upper Half Of Crankcase 



CMC 



Engine — Lecture IV Page 3 

called ball bearings. Their chief object being to eliminate friction. I will 
pass a plain and a ball main bearing among you for inspection. Other types 
of bearings such as roller and taper will be discussed in general later on, but 
as they do not enter into engine construction, we will drop them for the time 
being. 

Note to Teacher. — Oil grooves will be treated in the shop period on bearings. 

It may be well for us before closing this lecture to dwell a little upon the 
connecting rod. The large end which fits the crank-pin or shaft is similar to 
the main bearing and is scraped and fitted in the same manner. The small 
or upper end is fitted with another type of bearing called a bushing. Fig. 6 
is a perspective of the wrist or piston pin bushing, and is generally made of 
bronze. When it becomes worn it is replaced by another. The method of re- 
moval and replacement will be explained in detail during your shop exercise on 
this subject. 

To test to see if a connecting rod is loose, remove the lower crank case; take 
hold of the rod and see if there is any play, by a vigorous push up and down; 
if so, the looseness can be felt. Don't mistake the side play however for the 
looseness, as a slight amount of side play is necessary. There may be from 
1/64 to 1/16" play of the connecting rod parallel to the length of the pin. 
There may be as much as 3/16" play of the upper end of the rod along the 
piston pin or of the piston pin between the bosses. 

Connecting rod and main bearings may be adjusted without taking the en- 
gine out of the frame. However, this does not hold true where it is impossible 
to work at the engine from below. The following instructions will give a good 
idea how to proceed in order to properly adjust the connecting rod and main 
bearings in many of the modern engines. First: Drain off oil by removing the 
drain or pipe plugs from the bottom of the oil pan; then place a small lift 
jack under the pan to keep it from dropping before all of the oil pan bolts 
or studs that support it have been removed. If there is an oil float in the pan 
it is advisable to tie it up as high as possible to prevent it from dropping into 
the oil pan while the latter is being removed. It also makes it easier to replace 
the pan. Open all of the compression cocks on top of the cylinder. Second: 
After removing the oil pan it may be necessary to scrape the gasket off the 
bottom edge of the crank-case, and all dust and dirt must be cleaned away 
so that it will not get into the bearings. Clean hands and tools before work- 
ing on the bearings and never use any cotton waste or rags which might leave 
shreds behind as these cause serious trouble to the oiling system. Third : When 
working on bearings it is a good plan to pull out the pistons and clean off 
the rings and piston heads. Always oil the piston rings before replacing the 
piston. Fourth: In removing the bearing caps a socket wrench should always 
be used, as open wrenches are apt to destroy the nuts. Care should be exer- 
cised not to lose any of the shims and keep them in place until ready to remove 
them. Where laminated shims are used to take the loose play out of the bear- 
ings, the shim can be peeled off to the amount required to give the proper 
adjustment — never peel off more of the shim at one time than is necessary. 
Take out the shims that are necessary, being careful to remove an equal amount 
of shims on each side of the cap. Before replacing the cap see that the thin 
shims are placed between two heavy ones with which the connecting rods are 
always supplied. Replace the cap and draw it up as tightly as possible, using 
all four nuts and drawing them up evenly and firmly. After such bearing 
has been fitted and tested, draw up firmly all nuts, and if it is possible to obtain 
them, use new cotter pins only. Never back up the nut to insert the cotter 

CMC 



Engine — Lecture IV 



Page 4 



PLATE NO. 3. LECTURE NO. 4. 



Upper Crankoase 



Bearing Cap Stud 




•Bearing Cap 



FIG. NO. 3. 




Shim Space 



FIG. NO. 4. 
Note. — After bearing is scraped, shims are placed in the shim space. 



c M c 



Engine — Lecture IV Page 5 



pi ns — always draw up to the next notch and never use wire in the connecting 
rod nuts as it will interfere with the oiling system. Have the cotter pins well 
bent apart — so they cannot back out when the engine runs. 

Fitting connecting rod bearings. Remove oil pan and take off the bearing 
caps and remove piston. Take out bearing cap by removing the screws which 
hold it in place. The back side of the bearing must have a perfect or snug fit 
on the connecting rod, otherwise it will be impossible to get a perfect perma- 
nent bearing on the crank pin. Fitting the back of the bearing is practically 
on the same order as fitting the bearing to the crank pin. Using Prussian 
blue or red lead in the rod and cap will make possible the finding of the high 
spots between the cap and the bearings and these high spots must be draw- 
filed. This can be accomplished by placing the bushing in a vise and drawing 
the file across its face. No attempt should be made to file on the return stroke. 

Put in the screws very firmly and be sure that the heads are lower than 
the bearing surface so that they do not come in contact with the crankshaft. 
Next draw file across the top of the cap and the rod to have the bearing flush 
with the same. Without replacing the piston in the cylinder, fit the bearing 
to the crank pin. If the bearing it too wide the end will have to be draw filed. 
Be careful not to file too much off. By applying Prussian blue or red lead 
sparingly to the crank pin surface the fit of the bearing can be determined. 
Remove the rod and observe whether the blue or red "spottings" indicate a 
bearing the full length of the cap. If they do not the bearings should be 
scraped until a perfect bearing surface is obtained. 

Adjust the bearing to the crank pin so it can be moved to and fro freely, 
but at the same time it must not be loose. A very good test for proper tight- 
ness can be made by allowing the connecting rod with piston attached to assume 
an angle of about 45° from perpendicular with the crank shaft and at this 
angle the weight of the connecting rod and piston should make the bearing 
turn slightly on the crank pin. Remove the connecting rod and replace the 
piston in the cylinder giving the bearing the same adjustment as when the 
piston was out. Then turn the engine over by hand several times to make sure 
that no binding takes place. Do not be afraid of getting the connecting rod 
bolts too tight as the shims under the caps will prevent the metal from being 
drawn into too close contact. 



CMC 



Engine — Lecture IV 



Page 6 



PLATE NO. 4. LECTURE NO. 4. 




FIG. NO. 5. 
Sketch of Laminated Shim. 

PLATE NO. 5. LECTURE NO. 4. 




Wrist Pin Bushing. 



CMC 



Engine — Lecture V Page 1 






MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ENGINE SECTION 

LECTURE V 
Lubrication 

The purpose of lutmcation is to reduce friction. Friction is the force which 
retards the movement of one surface upon another. Wherever two materials 
are rubbed together, the friction between them generates heat. This idea is 
made a little clearer when it is remembered that the Indians used to rub two 
sticks together until the friction generated enough heat to cause the sticks 
to take fire. The same idea applies to metals. No matter how smooth a piece 
of metal may appear to the unaided eye, if looked at through a microscope, 
it will appear as rough as a file. Naturally, the smoother or more polished the 
metal is, the less friction will be caused; but no matter how "finished" the 
metal, friction, heat and wear will take place, unless some lubricant is used 
to prevent it. 

When a lubricant, as oil or grease, is placed between two metals, it fills all 
the microscopic depressions, and makes a smooth film between them. Theo- 
retically, therefore, two moving metal parts between which there is a film 
of oil, will not touch each other but will be prevented from actual contact 
and the resultant wear by the film of oil or other lubiicant. The more rapid 
the movement of the parts, or the greater the pressure, the more lubricant is 
required. A bearing in which a shaft is turning at a constant speed demands 
a constant supply of oil, which must be fed to it regularly as required. All 
moving parts of an automobile must be lubricated. The faster moving parts 
are subjected to greater heat than the others, and the form of lubrication 
must vary to suit the needs of those different conditions. In the gasoline en- 
gine, the parts move at very high speed. The heat thus generated added to 
the heat of the explosions, conducted through the metal, results in a high 
temperature. These pai'ts, therefore, must be supplied with a perpetual bath 
of oil while in operation. 

Various systems are used for supplying the parts of the engine with a plen- 
tiful supply of oil. These systems may be classified under main headings, 
namely, Splash systems and Force Feed systems. The "Simple Splash" sys- 
tem is obsolete, but will be described as it is the foundation of the circulating 
splash system. 

Simple Splash Syste7n. — In this system, the crankcase is filled with oil to 
such a depth that the bottom end of the connecting rod dips into the oil as 
it revolves, and splashes the oil to all parts of the crankcase bearings, and the 
fine spray or "oil-fog" caused by the lower part of the pistons when they are 
at the bottom of their stroke, is carried up into the cylinders. Thus the en- 
tire motor is lubricated by the splash created by the impact of the connecting 
rod bearings against the oil. 

As the oil in the crankcase is used up, more must be added to maintain the 
proper level. This may be accomplished by pumping it to the crankcase from 

CMC 



Engine — Lecture V 



Page 2 



PLATE NO. 1. LECTURE NO. 5. 



Sight Feed 



Overflow 







Df=l Oil Level Indicator 



Oil Level 



Cork Float 



Oil Sump 
Drain Cock 



Circulating splash oiling system. 



CMC 



Engine — Lecture V m Page 3 

a supply tank by a hand pump or by pouring oil into the breather pipe (open- 
ing in crankcase). 

While the simple splash system is quite satisfactory when the engine is 
level, the great drawback of this system is, that if the motor is inclined, as 
when the car is going up or down hill, the oil runs to one end of the crank- 
case or the other, so that there is no oil at the opposite end. Consequently 
the cylinder and bearings at one end get an over supply of oil, and those at 
the other, none, causing them to run dry and burn or seize, if the engine is 
in an inclined position for too long a time. This condition can be somewhat 
overcome by dividing the crankcase vertically by "baffle-plates," although this 
scheme only partly remedies the difficulty. On account of this danger, that 
all of the bearings will not get a sufficient supply of oil all the time, the simple 
splash system is now never used on automobiles. 

Circulating Splash (Pump Over). — This is a system which works on the 
same principle as the simple splash, but has improvements which overcome 
the disadvantages of the latter, and provide a constant supply of oil for all 
the connecting rod "scoops." "Oil-scoops" are usually attached to the con- 
necting rod bearing to assist in splashing the oil. These consist of a small 
piece of pipe about an inch long, which is threaded and screwed into the lower 
bearing cup. One side of the pipe is cut away, so that it has the appearance 
of a sugar scoop. The lower crankcase in this system is divided by an oil 
"pan," which has depressions, or troughs so arranged that when the pan is 
placed in the crankcase, these troughs come directly under the connecting rod 
bearings. A supply of oil is held in the crankcase beneath this pan. This 
lower space is called the "Sump" of the motor. An oil pump is used to draw 
the oil from the sump through pipes to the main crankshaft bearings. As it 
overflows from these bearings, it is thrown against the sides of the crankcase 
by the centrifugal force of the revolving crankshaft. 

"Oil gutters" on the sides of the crankcase, lead the oil down to all the 
troughs, under the connecting rods, which splash it to all parts of the motor 
as in the simple splash system. The main improvement of this system over 
the simple splash is that the troughs under the connecting rods will always 
have oil flowing into them at all times, no matter at what angle the motor 
may be, and a constant level of oil for each connecting rod "scoop" is assured. 
Holes in the "pan" allow the oil to return to the sump. 

The pumps are usually either of the "gear type" or the "plunger type." 
The gear pump consists of two spur gears which are "in mesh" with each 
other, and are turned by a shaft and spiral or bevel gears from the camshaft. 
As two spur gears turn in a close fitting housing the oil is carried by their 
teeth. The plunger pump is usually operated by an eccentric on the cam- 
shaft, which makes the plunger go up and down. This pump may be regu- 
lated by adjusting the length of the plunger, so that it will have a longer or 
a shorter stroke, and will consequently pump more or less, as desired. 

A cork float, together with a vertical wire which acts as a level-gauge is 
the usual indicator of the amount of oil in the sump or reservoir. The reser- 
voir should always be kept more than two-thirds full. A sight feed is also 
placed on the dash in front of the driver, so he can actually see the oil run- 
ning. If the oil stops running through the sight feed, the engine must be 
stopped at once, and the trouble located. A lack of oil in the crankcase, leaky 
connection in the oil pipe from the pump to the sight feed, dirt, or faulty 
pump may be the cause. A fine copper mesh screen is always located where 
the oil enters the pump, and this screen sometimes becomes clogged with dirt 

CMC 



Engine — Lecture V 



Page 4 



Oil Level Indicator 



Adjustable Pressure 
Relief Valve 



Drilled Oil 
Passage In 
Crankshaft 




Pressure Gauge 



Oil Supply- 
Main 



Oil Screen and Pump 



Main Engine Bearing 
Showing Oil Groove 
and Passage 





Oil Tube Along Rod 



m 



Overflow Through Hollow 
Piston Pin 



m 



Full Fores Feed Oiling System. 



C M C 



Engine — Lecture V Page 5 

which interferes with the circulation. The screen usually comes out with 
the drain plug and should always be cleaned when the oil is changed. 

Plain Force Feed System. — In this system, the oil is forced by a pump from 
the oil sump through tubes to the main crankshaft bearings and then through 
ducts drilled through the crankshaft to the connecting rod bearings. The oil 
flies from these bearings as they whirl around, and the oil is sprayed to all 
parts of the motor. This system very seldom uses the splash system in con- 
nection with the force feed, although it is sometimes done. In this case the 
oil would drip down and run into troughs, where it would be splashed by the 
connecting rod bearings. 

Full Force Feed. — This system uses a plunger-type pump which forces the 
oil under high pressure to the main bearings. From the main bearings, the 
oil is forced through the hollow crankshaft to the connecting rod bearings. 
A hole is drilled in the crankpin, and another in the bearing cap, as the crank 
revolves, the bearing is not only lubricated itself, but as the two holes come 
together each revolution, the oil is forced to the piston pin and bearings by 
a copper tube attached to the connecting rod. The excess oil at the connect- 
ing rod bearing is thrown against the side of the crankcase by the centrifugal 
force of the revolving shaft and splashes in a fine spray all over the interior 
of the engine. 

In the Pierce-Arrow and Packard Trucks, the oil pressure is adjusted by 
means of a pressure-relief valve, instead of by adjusting the length of the 
stroke of the oil pump. The pressure relief valve consists simply of a valve 
located near the pump and strainer on the side of the crankcase, and the ad- 
justment is by means of a nut increasing or decreasing the spring tension; the 
greater the tension, the greater the pressure. Instead of a sight-feed on the 
dash as in the circulating system, this system has a pressure gauge. This 
gauge should show a pressure from 5 to 30 lbs., according to the type of pump 
and speed of motor. Should the gauge show no pressure, the engine should 
be stopped at once, and the trouble remedied. Too much pressure may indi- 
cate a clogged pipe. The pressure may be regulated by adjusting the plunger- 
pump, as described before, or by adjusting the "spring and ball" if this type 
is used. 

Where the full force feed oiling system is used, the oil in the crankcase 
should be drained out, the crankcase washed with kerosene, and filled with 
fresh oil every 500 miles. In other systems, this should be done every 1000 
miles. 

The process of changing the oil is accomplished as follows: (1) Unscrew 
drain plug at bottom of oil sump, draining oil into pail or other receptacle. 
(2) Replace drain plug. (3) Pour about a gallon of kerosene into crank- 
case through the "breather" pipe. (4) Crank the engine for about a minute 
either by hand or starter. Do not start the motor under its own power. (5) 
Remove drain plug and allow kerosene to drain out completely. (6) Fill 
crankcase with fresh oil to the proper level. (7) Crank engine over several 
times before starting, in order to get the fresh oil into bearings, and started 
in its proper channel. 

Only the best grades of oil should be used in a gasoline engine. The oil 
should have good cohesion (vicosity) and a high flash-point and fire test in 
order to give proper lubrication in a motor for the heat in the cylinders 
(about 400° F.) will "break-down" or burn up a cheap unstable oil. An en- 
gine can be actually worn out in about one-third of its natural life by using 
poor oil. Follow the recommendations of the manufacturer in the matter of 
oil whenever possible. 

CMC 



Engine — Lecture V Page 6 

The use of a poor grade of oil, but especially a lack of sufficient oil will 
cause all the bearings and pistons to swell, and if allowed to run, the motor 
will be ruined by burnt out bearings and "scored" cylinders. Lack of suffi- 
cient oil can usually be detected by a smell of burnt oil coming from the en- 
gine and metallic "knocks." 

Unless an engine is new, or has very tight fitting pistons and rings, too 
much oil in the crankcase will result in an excess of oil working up into the 
cylinders, past the pistons and into the combustion chamber, where it will be 
burned, and leave a carbon deposit. No oil is able to withstand the heat of 
the combustion chamber, but the poorer oil, the greater the carbon deposit. 
If an engine gives trouble by constantly carbonizing and smoking, the trouble 
may not be too much oil, but leaky pistons and rings. If the oil is kept at the 
proper level in the crankcase, and the spark plugs are being constantly fouled 
and oil soaked, and carbon is formed rapidly and blue oil smoke comes out 
of the muffler, the trouble may be attributed to leaky piston rings, and per- 
haps pistons as well. New rings, or rings and pistons should be installed, as 
the case requires. After an engine has been run many thousand miles, es- 
pecially if poor oil has been used, the cylinders will be worn oval by the side 
thrust of the pistons. In this case, the cylinders must be rebored, and over- 
sized pistons fitted, or a new cylinder block and pistons installed. Badly 
scored cylinders will cause a bad leakage of oil into the combustion chamber. 
The cure for this trouble is the same as for the oval cylinders, although the 
use of heavy oil and a teaspoonful of graphite in the crankcase about every 
thousand miles will help somewhat. 

If it is not practicable to rebore the cylinders or fit new pistons, excessive 
"smoking" caused by the motor "pumping oil" up into the combustion cham- 
ber may be eliminated to a considerable degree by "champfering" (bevelling) 
the lower of the three compression rings at the top of the piston so that the 
oil will be collected in the little grooves formed by this process. Very small 
holes are then drilled through the piston at the bottom of this piston ring 
gx'oove at a 45° angle, so that the oil will run into the piston and back to the 
crankcase. Some manufacturers cut an extra groove in their pistons just be- 
low the upper ring grooves and drill holes in the extra oil-grooves for this 
purpose. 



c M C 



Engine — Lecture V 



Page 7 




GLAND NUT 



WATER PUMP 

CLASS B TRUCK 




I 



GOVERNOR 
CLASS B TRUCK 



CMC 



Engine — Lecture VI Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
ENGINE SECTION 

LECTURE VI 

Cooling System 

A cooling system is necessary for the proper working of a gasoline engine, 
because otherwise the very high temperature produced by the combustion of 
the gases in the cylinders would make the piston and cylinders red hot. This 
would, of course, destroy the lubrication and cause the pistons to "freeze," 
and would cause ignition of the mixture of fuel and air as soon as it entered 
the cylinder, or at least before the end of the compression stroke. This is 
avoided by providing a cooling system which consists of water jackets in 
which the water circulates about the cylinder wall and valves, a radiator for 
cooling the heated water, and some means of circulating the water through 
the system. 

Engine cylinders are sometimes cooled by air, particularly on motorcycle 
and light weight revolving cylinder airplane engines. Practically all trucks 
and cars used by the Quartermaster and by the United States Army are 
water cooled. 

Water cooling systems are divided into two classes, the forced circulation 
system and the thermosyphon circulation system. The latter is seldom used 
on trucks. In the thermosyphon system the water, which becomes heated in 
the jackets surrounding the cylinders since it is lighter than the cold water 
in the radiator, flows upward into the top of the radiator, and is replaced by 
cold water which flows from the bottom of the radiator into the jackets. This 
is exactly the same principle as is employed in circulating water from the 
back of a stove to the water tank in the hot water system in the kitchen. 

In the force system a pump, which may be driven by gear, chain or belt, 
draws the water from the bottom of the radiator and forces it through the 
water jackets around the cylinders and out into the top of the radiator. From 
there it flows down through the radiator and is cooled before reaching the 
pump, ready again to travel the same path. A fan, which is generally belt 
driven, is provided to draw the air through the radiator and is necessary to 
secure sufficient cooling, especially when the truck or car is driven with the 
wind or when it is operated in low gear. 

Proper temperature of cylinders has much to do with efficiency and smooth- 
ness of engine operations. If the cylinders are too hot, the engine will pound 
and the lubrication will not be satisfactory. If the engine is too cold, the fuel 
economy will generally be poor and the engine will not operate smoothly. If 
the temperature of the water is kept as high as possible, without the danger 
of boiling, better economy and smoother running will result. If, after the 
engine has made a long hard pull, the radiator is so cool that the hand may be 
placed on top of it without discomfort, it is almost a certain indication that 
fuel is being wasted. 

CMC 



Engine — Lecture VI 



Page 2 




u 
o 

A 



CMC 



Engine — Lecture VI Page 3 

The motometer or radiator -thermometer is used to indicate the radiator 
temperature and its purpose is to prevent serious trouble by informing the 
driver that the water is boiling or that the water is too cool for efficient 
operation. 

A device known as a thermostat is sometimes provided for regulating the 
temperature of water which circulates around the cylinders. It prevents the 
water from flowing through the radiator and becoming cooled until the desired 
temperature has been reached, and then maintains that temperature. Some- 
times a permanent shutter arrangement, or simply a curtain or piece of card- 
board, is used to cover a portion of the radiator and prevent over-cooling of 
the engine in cold weather. 

The radiator for a truck may be of either honey-comb or tubular construc- 
tion. The cellular or honey-comb radiator is composed of a great number of 
cells through which the air is drawn by the fan or driven by the speed of the 
machine. The construction of a honey-comb radiator is rather delicate, and 
when such a radiator is used on a truck it is generally supported on special 
springs to relieve it of part of the road vibration and of some of the twisting 
action to which it would be subjected if rigidly bolted to the frame. 

Tubular radiators may be made with a great number of vertical tubes pro- 
vided with a series of continuous horizontal fins to increase the cooling effect, 
or each tube may have independent fins. 

Recently a great number of truck manufacturers have adopted radiators 
built with removable top and bottom plates to permit easy inspection, cleaning 
and repair. 

Care should always be taken to avoid filling the radiator with water which 
contains too much lime or scale-forming matter. Water which produces a 
thick deposit of lime in the tea kettle will do the same in the water jackets and 
probably in the radiator. 

The stuffing boxes or glands on the water pump should be kept properly 
adjusted, that is, just tight enough to prevent leakage. The grease cups for 
lubricating the pump shaft should be given proper attention faithfully every 
day. 

In winter unless an anti-freeze solution with sufficient strength to prevent 
freezing, is used, special precaution should be taken to prevent the freezing 
up of the cooling system. If plain water is used, it is a very common custom 
to drain the radiator at night and to refill it in the morning. When a drain 
cock has been opened, it is generally necessary to run up a wire to remove 
stoppages caused by sediment. When the water stops flowing, the wire should 
be tried again so that the driver may be sure that no water remains. On 
some engines it is necessary to drain at more than one point in the system. 
Suitable cocks or drain plugs are provided at the bottom of not only the radia- 
tor, but also the water pump, the lower water pipes and the cylinder jackets. 
After the draining is completed, it is advisable to run the engine for a few 
seconds to make sure that the water pump housing is clear. 

At the front the drivers have made a practice of cutting off the fuel supply 
at the main tank, running the engine until the carburetor is dry, and then 
placing one or two kerosene side lamps beneath the hood, and blanketing the 
hood and radiator to prevent danger from frost. 

When the weather is below freezing, anti-freeze solutions are often used. 
Such substances as alcohol, glycerine, calcium-chloride and water are used. 

CMC 



Engine— Lecture VI Pa 9 e 4 



Calcium-chloride is objectionable because it has a destructive corrosive and 
electrolytic action on some of the metal parts with which it comes in contact 
in the cooling system, particularly on aluminum or cast iron. 

Alcohol evaporates very easily and constant attention is needed to keep the 
solution strong nough to give the proper protection. Alcohol is desirable be- 
cause it has very little effect on metal or on rubber connections. 

The freezing temperatures for alcohol and water solutions of different 
strengths are as follows: 

25% Alcohol for 0° Fahr. 

30% " " 5° below zero Fahr. 

40% " " 20° " 

60% " " 45° 

A special form of hydrometer is sometmes used to indicate the percentage 
strength or the freezing point of an alcohol solution. 

A mixture of glycerine and water, or possibly better, a mixture of glycerine, 
alcohol and water is desirable because the glycerine does not boil away. Un- 
fortunately the cost of glycerine makes the use of this solution prohibitive. 

When a solution containing a considerable amount of alhocol or of glycerine 
freezes, the ice formed will be soft and mushy much like frozen milk and 
generally no breakage will result provided the water is thawed with a tea 
kettle full of hot water or a blow torch before an effort is made to crank the 
engine. It is advisable to blanket the radiator and allow the engine to run idle 
until the entire radiator has become warm before the truck is driven in the 
cold. 

If a radiator has sufficient capacity to cool an engine properly in the sum- 
mer time when the temperature is as high as 90 or 100° F., approximately half 
this capacity will be needed in zero weather if the engine is to be operated 
at the same desired working temperature. The driver can control the tem- 
perature by covering the lower half of the radiator or the lower half and part 
of the side of the radiator on which the carburetor is located. 

When a radiator begins steaming in cold weather it is generally an indica- 
tion that it has frozen and it should be blanketed immediately and the engine 
allowed to run idle until it is warm throughout the entire face. 

Boiling of the radiator is an indication of some form of trouble. This 
trouble may be due to a great many causes outside of the cooling system. 
Driving with the spark lever in retarded position (or with the spark advance 
rod disconnected) , or prolonged driving in low gear will generally cause boil- 
ing. A mixture entirely too rich or entirely too lean may be the cause of boil- 
ing. A loose fan belt, a broken paddle wheel in the water pump, or an insuffi- 
cient supply of water in the radiator might also cause boiling. Obstructed 
exhaust pipe, a dirty muffler, improper valve timing, may also have the same 
effect. In zero weather overheating is generally the result of frozen radiator, 
frozen water pipes, or inoperative water pump. 

The majority of cooling system troubles can be warded off if a certain 
amount of care is exercised in operating the car. 

However, it will be well for us to refresh our minds with the most important 
troubles concerning radiation. The most frequent is a leak, which may be 
repaired in the following manner. 

If it is a slight leak the tube can be closed by a pair of pliers; if the seams 
of the tube open, it will require a section of new tube. The most important 
repair work in connection with radiators is soldering and one must be quite 

CMC 



Engine — Lecture VI Page 5 

an expert to do this in a satisfactory manner. On the class "B" Military 
Truck, if the tubes leak the cast iron header is removed and the tubes are 
flanged so they will conform with their seat in the shell casting. In repairing 
the radiator I have used small white pine plugs, inserting them in the section, 
and when they became water-soaked they expanded and choked the leak. In 
this manner entire sections can be blocked off making a very substantial tem- 
porary repair. 

Hose connections are also troublesome at times. Emergency repairs such 
as taping the manifold, and giving it a coat of shellac, or replacing the hose, 
do not require skilled mechanics. These connections should be thoroughly 
inspected quite regularly. 

In the water pump we sometimes find broken impellers or gears, sheared 
shafts and stripped packing gland nuts. A broken shaft gear or impeller is 
indicated by a very hot motor with a remarkably cool radiator and must be 
replaced. A damaged stuffing box nut can be temporarily repaired by peening. 
Should the packing gland require new packing, the nuts are backed off, the 
packing placed around the shaft so that it is wrapped in the same direction 
that the nut is turned when replaced and tightened up. This nut should be 
tightened just enough to stop the leak. Briefly, we have outlined the general 
troubles, and the shop practice on this subject will enable you to make these 
repairs. 



CMC 



Engine — Lecture VII Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ENGINE SECTION 

LECTURE VII 

Camshaft and Crankshaft 

The next step in the construction of the engine is the camshaft and its rela- 
tion to the crankshaft. Needless to say it is mounted in bearings and located 
within a reasonable distance from the crankshaft. Our first determination is 
its speed. As the admission of the charge is the first function to perform we 
can readily start with the inlet camshaft. You will remember that the inlet 
valve opened shortly after top center and remained open until 38 ° after bottom 
center. 210° of one revolution is consumed in this stroke or slightly over one- 
half a revolution. As will be remembered there are three other functions to be 
performed in two revolutions, namely, compression, ignition and exhaust. This 
very fact sets up a ratio of % or 1 : 4 and as the inlet valve opens once in 
every two revolutions of the crankshaft, the camshaft revolves once. A ratio 
of 2 to 1. In plain the diameter of the camshaft gear is twice the diameter 
of the crankshaft gear. 

To tell you here that in modern design a greater number of gears are used, 
and to explain why an intermediate gear simply changes direction and does not 
influence speed, or why a compound train accomplishes the same result as a 
2 : 1 ratio, would lead you into teachnical discussion which is to be avoided at 
present. 

As to the construction of the camshaft, most engines' cams are integral with 
the shaft. The shape of the cam should be such that there will be no hammer- 
ing action when the valve is first lifted from its seat and that it will be eased 
down against its seat instead of dropping against it with a hammer blow under 
the influence of the stiff spring. 

While the camshaft practically gives no trouble there are at times repairs 
to be made, such as replacing a bearing or lining up a shaft and also the dress- 
ing of the teeth on the camshaft gear. In most motors, especially when they 
are new, gears sometimes are a few thousandths too deep in mesh. This can 
be remedied by pulling the gear and re-machining it or by mill filing. As this 
seldom occurs we will not dwell upon it any longer. There are no particular 
troubles attached to the camshaft so we will embrace the timing of the shaft. 

As a general rule all camshaft gears, when timed by the manufacturers, 
are marked; however, should it occur that a gear becomes broken in such a 
way that it was impossible to determine the timing with the gear on the crank- 
shaft, we would have to determine first the firing sequence of the engine. 
Assuming that this sequence were 1, 3, 4, 2, the next step would be to bring, for 
convenience we will say, piston No. 1, to top dead center on admission stroke. 
This would mean that the both valves were closed and the piston about to start 
its power stroke. At this point we turn the flywheel clockwise to approximately 
46° before bottom center unless otherwise specified by the flywheel mark. At 

CMC 



Engine — Lecture VII Page 2 

this point the exhaust valve should start to open. It can be readily judged by 
the valve tappet clearance. Assuming that the gear on the inlet camshaft 
was broken, the procedure is practically the same, as you must determine first 
the firing sequence in order that the cylinder selected should be on top dead 
center. Then revolve the flywheel to the point of valve opening and place the 
gear in mesh. It may also be mentioned in this lecture that back lash is often- 
times present and can only be remedied by setting the crankshaft closer to the 
gears, bringing the crankshaft gear deeper in mesh with the timing gear, 
or by replacing the worn gears with new ones. 



CMC 



Engine — Quiz Questions Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ENGINE SECTION 

Quiz Questions 

1. Name the operations which take place in the cylinder of a gasoline 
engine. 

2. What is meant by cycle? 

3. What would the objection be to a single engine for propelling a motor 
car or truck? 

4. How far apart will the explosions occur in a single cylinder engine? 

5. In a four-cylinder engine? 

6. In a six? 

7. In a twelve? 

8. Name the essential parts of a single-cylinder engine. 

9. From what material are cylinders made? 

10. Pistons? 

11. Piston rings? 

12. What difference is there between the condition of the surfaces which 
slide or turn one against the other in a new engine and in an old engine? 

13. What precaution should be taken when the engine is new to prevent 
injury to cylinder walls and bearings? 

14. If sand, grit or fine material dust is allowed to remain mixed with oil 
and is pumped into the bearings, what will be the result? 

15. What is the name applied to the noise made by a loose piston? 

16. How does it sound? 

17. What kind of a noise will be made if the cylinders are scored or the 
rings are a bad fit and the compression leaks by the piston into the crank case? 

18. Name three classes of compression leaks. 

19. How can it be proved definitely whether the loss of compression in one 
cylinder is due to the leakage past the piston or leakage past the valves? 

20. How much compression should be used? 

21. Explain definitely how the compression should be tested in one par- 
ticular cylinder of the engine. 

22. From what material are connecting rods made? 

23. If cylinders are handled roughly when lifted from the engine or re- 
placed and the rods are bent, what effect may this have on the quietness of 
the engine? 

24. On the bearings? 

25. With what material is the lower end of the connecting rod lined where 
it joins the crankshaft? 

CMC 



Engine — Quiz Questions Page 2 

26. If the engine is run with insufficient lubrication what will happen to 
this bearing? 

27. How can a knock caused by a loose connecting rod be distinguished from 
one due to some other cause? 

28. Explain one method of testing for loose connecting rods without 
dropping the crank case. 

29. From what material is the piston or wrist pin made? 

30. What kind of a noise will be made by a loose-fitting piston pin? 

31. How can you locate the cylinder in which the pin is loose? 

32. What must be done with the oil in the engine base from time to time 
in order that it may be able to lubricate the bearings properly? 

33. Mention two reasons why the old oil may be unsatisfactory. 

34. Which pistons move up and down at the same time in a four-cylinder 
engine? 

35. In a six-cylinder engine? 

36. What is the rotation of explosions in a four? 

37. How can you determine the firing order in a four, six, eight or twelve- 
cylinder engine? 

38. If a flywheel is not securely fastened to the crankshaft what kind of a 
noise will result? 

39. How fast does the camshaft in an engine turn? 

40. What is the name of the part which is interposed between the cam and 
valve stem of an ordinary L-head or T-head engine? 

41. How much clearance should be allowed between an inlet valve stem and 
a push rod? 

42. What is the reason for this clearance? 

43. Would it be necessary to set as much clearance for an inlet as for an 
exhaust? 

44. What is the thickness of an ordinary piece of newspaper? 

45. A space of the thickness of how many of these newspapers would it be 
safe to use in adjusting clearance on an inlet valve? 

46. On an exhaust valve? 

47. Would the same amount of clearance be needed between a rocker arm 
and valve stem in a valve-in-the-head engine where the valve-operating mechan- 
ism is exposed? 

48. If the adjustment of a push rod is too loose, what kind of a sound will 
result? 

49. How can this be distinguished from the sound which results from a 
loose rod or other engine bearing? 

50. What is the special advantage of an L-head engine for a truck or tour- 
ing car as compared with a valve-in-the-head engine? 

51. State in a very few words the advantages and disadvantages of both 
types of engines. 

52. From what material are exhaust valves often made in order that they 
may withstand the heat without warping? 

53. What is the result of a warped or carbonized valve? 

54. What operation is performed on the valves of an engine to make them 
fit perfectly tight against their seats? 

CMC 



Engine — Quiz Questions Page 3 

55. If valves become interchanged after they have been ground will they fit 
properly? 

56. When valves have been ground what attention should be given to the 
clearance? 

57. What materials are commonly used for grinding valves? 

58. Explain the method of valve grinding. 

59. What would be the result of an attempt to grind valves in with an elec- 
tric drill or by giving them a continuous rotary motion with a breast drill? 

60. What is the object of lifting the valve and turning it to a different posi- 
tion frequently during the process of valve grinding? 

61. What is often placed around the stem of a valve beneath the head 
when it is being ground in, and what is the purpose? 

62. What precaution should be taken with the valve stem and guide after 
the grinding operation is completed? 

63. What will be the result if a stem has been sprung and binds in the 
guide? 

64. What could be placed on the valve stem to indicate where it rubs? 

65. Explain the method of determining whether a valve is a perfect fit 
against the valve seat. 

66. What is the effect of an inlet valve stem which is entirely too loose 
a fit? 

67. Under what conditions will it have the most effect upon the running 
of an engine? 

68. What can be done as a temporary remedy for a weak valve spring? 

69. Would it be better to have a weak valve spring on an inlet or on an 
exhaust? 

70. What will be the effect of a broken exhaust valve spring? 

71. What is the method for temporary repair? 

72. At what two places are marks generally placed on an engine to indi- 
cate whether the valves are properly timed? 

73. Which event of which valve would be the best to be guided by in replac- 
ing cam shaft driving gears or chain in an unmarked engine? 

74. What time should this event occur? 

75. What are the two methods of causing the water to circulate through the 
water jackets and radiators? 

76. Compare very briefly the advantages of the two methods. 

77. Would it be better to have the water in the cylinder always so cool 
that you could comfortably bear your hand on the top of the engine block or the 
top of the radiators? 

78. Why? 

79. What would be the effect of running the cylinders at a very much 
higher temperature even than that attained in the air cooled engine? 

80. What will be the result if impure water is used in a radiator? 

81. How are truck radiators often constructed to make cleaning easier? 

82. What precaution will generally be found necessary after the drain 
valve is open to insure draining? 

83. How often will it be necessary to repeat this? 

84. How are truck radiators often supported to relieve them of road shock? 

CMC 



Engine — Quiz Questions Page 4 

85. What effect will this have on hose connections? 

86. Where should spare hose connections be kept? 

87. What can be used as a substitute for a broken hose clamp? 

88. What attention will the water pump require? 

89. What material can be used in an emergency for packing? 

90. Will it make any difference which direction the packing is wound around 
the shaft? 

91. What material should be used on the packing to lubricate it and prevent 
wear of the shaft? 

92. Which direction do the packing nuts on a pump turn? 

93. If a car has stood in the cold for some time, where will ice form first? 

94. How should a driver determine whether there is ice in the water pump 
before he attempts to crank the engine? 

95. How should it be thawed? 

96. In a car which has a water pump what is the simplest test to deter- 
mine whether or not the water circulates? 

97. In a car with thermosyphon circulaton what will be the result of a 
low level of water in the radiator? 

98. Name six possible causes for the water boiling in the radiator. 

99. What may happen to one or more tubes in a radiator which will cause 
them to leak badly even if the precaution has been taken to drain carefully? 

100. If one tube in a radiator is injured, explain the method of temporary 
repair. 

101. If a small portion of a honeycomb radiator has been injured explain 
the method for temporary repair. 

102. What precautions are generally taken when a car is to be driven in 
cold weather? 

103. Which portion? 

104. How much? 

105. When it is to stand for a short time? 

106. Where will freezing take place first? 

107. If a radiator begins to steam while the car is under way, due to freez- 
ing, what method of procedure should be followed? 

108. What is the advantage of maintaining a high but uniform temperature 
of water in the jacket at all times? 

109. Explain what a thermostat does. 

110. Explain the operation of radiator shutters. 

111. What advantage is a motometer or radiator thermometer,? 

112. Name four substances in use to prevent freezing up in the cooling 
system. 

113. State briefly the advantages and disadvantages of each. 

114. What will be the results if two dry metal surfaces are rubber one 
against the other? 

115. If two surfaces which look to be highly polished are examined with 
a strong magnifying glass, how will they appear? 

116. What must the oil or grease do to each of these surfaces? 

CMC 



Engine — Quiz Questions Page 5 



117. If the oil produces the proper film and prevents metal to metal contact, 
should there be any wear? 

118. How long would an engine run with no oil on the bearings? 

119. What effect may the dust drawn in with the air through the carbu- 
retor have on the cylinder walls? 

120. What is often the real nature of the so-called carbon deposit? 

121. What may be done with an engine every night to prevent accumula- 
tion of carbon? 

122. What is the first indication a skilled driver will notice if the piston 
and cylinders are insufficiently lubricated? 

123. What will be the feel of the engine if the switch is turned off and the 
crank turned by hand? 

124. If an attempt is made to continue to drive an engine until the cylinders 
become perfectly dry, what will be the result? 

125. State definitely what procedure should be followed when the engine 
has seized or is frozen. 

126. Explain the different types of devices which may be found on the 
dash to permit the driver to know what oil is being supplied to the engine 
bearings? 

127. What provision is made to permit the driver to ascertain the amount 
of oil in the engine base? 

128. How often is it advisable to investigate the amount of oil? 

129. What attention does the oiling system of a new engine require? 

130. Why? 

131. When an engine does not use up its lubricating oil rapidly, what may 
be the condition of the oil? 

132. What is the cause of this condition? 

133. What is the cause of water or ice in the crank case or oil pump? 

134. What attention should the oiling system be given? 

135. How often? 

136. Explain the operation of a splash oiling system, such as is used on the 
Ford. 

137. Of a circulating splash oiling system. 

138. In a system of this type what device is usually provided on the dash 
to inform the driver that oil is being supplied? 

139. Explain the operation of a full forced-feed oiling system. 

140. What device is placed on the dash to inform the driver that it is in 
operation? 

141. If the pointer vibrates, what may be the trouble? 

142. If the gauge or sight feed on the dash indicates that oil is not being 
supplied, what should be done? 

143. When? 

144. If there is found to be a supply of oil in the engine base and the sight 
feed or gauge on the dash indicates that it is not being pumped to the bearings, 
what may be the cause? 

145. What may be necessary to cause the pump to begin to work again? 

CMC 



Engine — Quiz Questions Page 6 

146. If the oil pump has failed and cannot be made to circulate the oil, 
what can be done to allow the truck or car to be driven to the repair shop 
without the danger of burning out a bearing? 

147. In a full-forced-feed system what will be the effect of a loose bearing? 

148. If a rod bearing has been run with insufficient oil or has been too tight 
what may happen which will prevent its receiving oil? 

149. Why will a spark plug with a cracked porcelain cause one cylinder to 
be flooded with lubricating oil? 

150. Will it be better to have the oil in the engine base hot or compara- 
tively cool? 

151. In what condition will the lubricating oil generally be in, in zero 
weather? 

152. What precaution will be necessary before the engine is raced or the 
truck driven? 

153. What will be the result if this precaution is neglected? 



CMC 



Ignition — Lecture I Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
IGNITION SECTION 

LECTURE I 

Electrical Equipment 

Starting with nothing more than a few dry cells and a wiring system that 
would shame the average bell hanger, the electrical equipment of the auto- 
mobile has constantly increased in importance until within the last few years 
it has become the most essential auxiliary there is on the motor car. 

Even in the present highly perfected state, it still constitutes the weakest 
element among the motor auxiliaries; in fact, it is subject to more defects than 
any other single element of the entire construction. This must not be taken 
as implying that it is defective in any sense, as it is quite the contrary, but 
owing to its nature, it is more susceptible to derangement. For this reason, it 
behooves the student to give more than the usual amount of attention and 
study to this branch of the subject. 

To acquire a good, practical working knowledge of electricity as applied to 
the motor car, it is essential not merely to find out how things are done either 
by watching the other fellow do them or by studying pictures in a book, but 
also to learn why certain things are done and why they are carried out in just 
such a way. In other words, the man whose knowledge is based upon theory 
and principles applies knowingly the cause to produce the effect, and is certain 
that the desired effect will be produced. On the other hand, the man who 
works only with his hands goes aimlessly from one thing to another, trusting 
chiefly upon luck to accomplish the result. 

There are accordingly two distinct classes of knowledge in regard to this 
equipment; one which is picked up at random, an isolated point at a time and 
applied in the same manner, and the other which is based upon a clear insight 
into the underlying reasons for the various actions and reactions that make up 
the different electrical phenomena involved. If we want to know what is 
wrong with an electric motor, it is essential that we should know what makes 
an electric motor operate when everything is right; and in the same way, it 
would be groping in the dark to attempt to investigate the reason for the 
failure of a dynamo to generate current, or a storage battery to give up its 
charge if we had no knowledge of why a dynamo, when run by an outside 
source of energy normally produces a current, or why a battery literally gives 
back what has been put into it when its current is closed after charging. 

It will accordingly be the function of this lecture to give a brief resume of 
the principles underlying the operation of what has become the most impor- 
tant auxilary of the motor car, its electrical equipment. Contempt of book 
knowledge is not wholly a thing of the past, and many men consider themselves 
practical by insisting upon learning how to do things with their hands alone. 
The authority, however, is the man who uses his head to acquire knowledge of 
the theory upon which practice is based and then employs his hands to much 
better effect by letting his brain guide them. 

CMC 



Ignition — Lecture I Page 2 

Electricity 

Just what electricity is we do not know — maybe we never shall know, but 
it is a matter of common knowledge that it is one of nature's prime forces, 
and as such is universal. The air, the earth, the water, the clouds, our bodies 
and those of animals and other inanimate objects, such as trees, houses and the 
like, are all electrified to a greater or less degree all the time. The amount of 
electricity that any given object possesses at a given moment depends upon its 
capacity and the conditions surrounding the object. For example: a room will 
hold a certain amount of air; if it is not influenced by other conditions, we 
know that the room is full of air at atmospheric pressure. The room may be 
considered in a normal stage of charge. 

There is nothing that differentiates the air in this room from that of the ad- 
joining room. It is perfectly quiet and nothing is disturbing it. There is no 
tendency for it to move. If, however, all the openings of the room are tightly 
closed, with the exception of a duct, for the admission of more air under the 
influence of a powerful compressor, in a very short time there will be a marked 
difference between the air in this room and the air in the other room. Instead 
of the normal atmospheric pressure of 15 lbs. per square inch, there will be a 
pressure against all parts of the room of 50, 60 or 100 lbs., according to the 
length of time the compressor has been working and the degree of tightness 
with which the various openings have been closed; thus there will be a great 
deal more air in the one room than its neighbor. If it were electricity instead 
of air, the room would be said to be highly charged. 

The air in this room on account of the pressure which it is under is con- 
stantly seeking an outlet, and it will gradually leak out through various small 
openings, probably without its escape being noticed. The same conditions ob- 
tain when a body becomes electrified beyond its capacity to hold a charge. The 
charge of electricity will leak away without giving any indication of its pass- 
ing. Returning again to the room containing the compressed air, if a door or 
a window of that room is opened suddenly, the pressure is immediatley re- 
leased through that opening and anyone standing in front of it would say 
that a strong current of air blew out. In the case of electricity, if any easy 
path of escape is provided, the entire charge will rush away from the body, and 
there is then said to be a current of electricity flowing from the point of escape 
to whatever object equalizes the pressure by becoming charged. An electric 
current is accordingly electricity in motion. It is simply said to flow, but to 
cause it to do so, there must be pressure. This electrical term is known as 
voltage. 

Every day in the year the earth transmits a greater or less proportion of 
its electrical charge to the atmosphere or receives a charge from the latter, 
but unless the conditions are favorable, there is no visible indication of this 
difference. It must be borne in mind that this difference of electrical pressure 
between two points is what causes the current to flow. Given a hot summer's 
day, however, when the air is heavily charged with moisture or rain, clouds 
form in great masses, then the electrical charges from the earth and the air 
accumulate in these great banks of water vapor instead of passing up to higher 
regions of the atmosphere. When the charge exceeds the capacity of the clouds 
and the electrical pressure between two neighboring clouds or between a cloud 
and the earth becomes very great, we have the familiar phenomena of light- 
ning, the electricity escaping in a several mile long flash. 

It is thus apparent that electricity is an element that can be expressed in 
quantity and one that likewise can be subjected to pressure. The unit of 

CMC 



Ignition — Lecture I Page 3 

quantity is the coulomb; the unit of pressure is the volt; the unit of current 
is the ampere, equal to one coulomb per second. Presuming the simile pre- 
viously given, 500 cubic feet of air per minute forced into a room under 100 
lbs. pressure may be likened to a current of 500 amperes at 100 volts, and just 
as the opening allowed determines the rate at which the air will escape, so 
the electrical outlet influences in the same manner the current that will flow. 
From this it is evident that there is another factor to be considered — this is 
resistance. 

If a half-inch hole is bored in the door of the room, the air will escape at a 
pressure of 100 lbs. per square inch, but only a few cubic feet per minute can 
pass through this orifice. If a very fine wire is used to tap the given charge 
of 500 amperes at 100 volts, the current will have a pressure of 100 volts, but 
very few amperes will pass through the fine wire. If the pressure back of the 
air is increased, however, more air will be forced through the small opening 
in the same time, and if there is a greater pressure back of the electric current, 
more current will be passed through the fine wire. Thus the factors of pressure 
and flow are related and are dependent upon the factor of resistance. The 
unit of resistance is the ohm. 

Ohm's Law 

For this inter-relation has been deduced what is known as "Ohm's law," 
usually expressed as I equals E divided by R or current equals voltage 
divided by resistance. 

As a practical application of the preceding formula, take the case of a 
small conductor connecting the battery and the starting motor of the electrical 
starting system. The diameter of the wire is such that the length required 
to connect the two points has a resistance of 10 ohms. One ampere is that 
amount of current which will pass through a conductor having a resistance of 
one ohm under a pressure of one volt. The starting system in question oper- 
ates at six volts. Hence, I equals six tenths, equals .6; that is, the battery 
would be able to force only .6 ampere through that small wire and the starting 
motor would not operate. It is apparent from the foregoing that the formula 
for Ohm's law may be transposed to find any one of the three factors that may 
be unknown; for example: Given the conditions just mentioned we may deter- 
mine how much resistance the wire in question has. The resistance equals the 
voltage divided by the current, i.e., R equals E divided by I or, resistance equals 
6 divided by .6, equals 10 ohms. 

Or again, if it is desired to learn what voltage is necessary to send a current 
of .6 ampere through a resistance of 10 ohms, the solution calls for an equally 
simple transposition of the formula; therefore, given any two factors, the 
third may be readily determined. 

Ohm's law is absolutely fundamental in all things pertaining to electrical 
operation, and the man who wants to make his knowledge of the greatest 
practical use will do well to familiarize himself with it. Naturally, it does 
not enter into the repair work to more than a small fraction, but a knowledge 
of it is of distinct value. 

Power Unit 

To go back to the room under pressure, it is apparent that the energy re- 
leased by the lowering of this pressure may be made to perform useful work, 
such as driving a compressed air drill, running a small air motor, or the like, 

CMC 



Ignition — Lecture I Page 4 

so with the electrical circuit, the drop from a higher to a lower voltage which 
causes a current to flow is a source of power. Electrical power is the product 
of the ampere multiplied by the voltage at which it is applied. The power unit 
is the watt, and it is equivalent to one ampere of current flowing under a 
pressure of 1 volt. There are 746 watts in a horse power. The power equiva- 
lent is expressed as P equals I multiplied by E. For example: How much 
power is developed by a 6-volt starting motor if 125 amperes of current are 
necessary to turn the engine over fast enough to start it? The amount of 
current given is an arbitrary average taken simply for the purpose of illus- 
tration, for in overcoming the inertia of an automobile engine, a great deal of 
current is required at first, the drain on the battery oftentimes exceeding 250 
amperes for a few seconds, then dropping as the engine turns over to about 
50 or 60 amperes. So, taking 125 as the average, we have 125 times 6 equals 
750 watts, or slightly over 1 H.P. 

Granting that 1 H.P. is necessary to turn over a 3% by 4" six cylinder 
motor at 75 R.P.M., a speed that has been pre-determined as necessary to cause 
it to take up its own cycle under the most adverse starting conditions, and given 
a six-cell storage battery capable of developing a potential of twelve volts, 
then we have I equals P divided by E, or current equals 746 divided by 12, 
equals 62.1 amperes, which represents the average demand upon the storage 
battery to start the engine under normal conditions. This illustration and 
the previous one shows the working of Ohm's law, doubling the voltage as 
the amount of current necessary. As the life of a storage battery is largely 
determined by the rapidity as well as by the number of its discharges, and 
as the storage battery is the weakest element in any electric system, I will 
now proceed to outline in general the fundamental principle of a storage 
battery. 

The Battery 

The storage battery is the business end of every electrical starting and 
lighting system. Just as the most elaborate and reliable ignition apparatus 
is of doubtful value with poor spark plugs, so the finest generators become use- 
less if the battery is not in proper working order. A little experience in the 
maintenance of electric starting and lighting systems will demonstrate very 
forcibly that the relative importance of the battery is totally disproportionate 
to that of all the remaining elements of the system put together; the latter 
essentials have been perfected to a point where they will operate efficiently 
without attention for a long period. The battery, on the other hand, requires 
a certain amount of attention at regular and comparatively short intervals. 
Usually this attention it not forthcoming, or it may be applied at irregular 
intervals, and with but scant knowledge of the underlying reasons that make 
it necessary, consequently the battery suffers. It is abused more than any 
other single part of the entire system, and not being so constituted that it can 
withstand the effects of this abuse and still operate efficiently, it suffers 
correspondingly. 

In the sense in which it is commonly understood, a battery does not actually 
store ' a charge of electricity, the process is entirely one of chemical action 
and reaction. A battery is divided into units, termed cells; each cell is com- 
plete in itself and is uniform with every other cell in the battery, and one of 
the chief objects is to maintain its uniformity. Each cell consists of certain 
elements which, when a current of electricity of a given value is sent through 
them in one direction for a certain length of time, will produce a current of 
electricity in the opposite direction if the terminals of the battery are con- 

c M c 



Ignition — Lecture I Page 5 

nected to a motor, lamps, or other resistance. The cell will, of course, also 
produce a current if its terminals are simply brought together without any 
outside resistance; this, however, would represent a dead short circuit, and 
would permit the battery to discharge itself so rapidly as to ruin its elements. 
This is one of the things that must be carefully guarded against. When attend- 
ing a battery, see that its terminals are not left exposed where tools may 
accidentally drop upon them. When the current is being sent into the battery, 
as previously mentioned, it is said to be charging. When it is connected to an 
outside resistance, it is discharging. 

The Elements 

The elements are known as the positive and negative plates. They consist 
of a foundation which is a casting of metallic lead in the form of a grid, the 
outer edges and the connecting lug being of solid lead, while the remainder of 
the grid is like two sections of lattice work, so placed that the openings do not 
correspond. The object of giving them this form is to make the active mate- 
rial of the plates most accessible to the electrolyte or solution of the battery, 
and at the same time to insure retaining active material between the sides of 
the grid. 

This active material consists of peroxide of lead in the positive plate and a 
spongy metallic lead in the negative plate. The active material is forced into 
the grid under heavy pressure, so that when the plate is completed it is as hard 
and smooth as a piece of planed oak. The positive plate may be distinguished 
by its reddish color, while the negative is a dark grey. Each positive plate 
faces a negative plate in the cell, and as the capacity of the cell is determined 
by the area of the positive plate, there is always one more negative than 
positive. The lead connector of each of the plates is burned to its neighbor 
of the same kind, thus forming the positive and negative groups which con- 
stitute the elements of the cell. 

Separators 

As the elements must not be allowed to come in contact with each other in 
the cell because to do so would cause an internal short circuit, and as the 
maximum capacity must not be obtained in the minimum space, the plates are 
placed very close together with wood and perforated hard rubber separators 
between them. These are designed to fit very snugly so that the combined 
group of positive and negative plates is a very compact unit. When re-assem- 
bling a cell, it is very important that these separators be properly cleaned 
and not broken. 

Electrolyte 

To complete the cells, the grouped elements with their separators are im- 
mersed in a jar holding the electrolyte. This is a solution consisting of water 
and sulphuric acid in certain proportions, both the acid and the water being 
chemically pure to a certain standard. In mixing electrolyte, the acid must 
always be poured into the water. Never attempt to pour water into the acid, 
but always add the acid a little at a time to the water. The addition of the acid 
to the water does not simply make a mechanical mixture of the two, but 
creates a solution in the formation of which a considerable amount of heat is 
liberated. Consequently, if the acid be poured into the water too fast, the 
containing vessel may be broken by the heat. For the same reason, if the 
water be poured into the acid, the chemical reaction will be very violent, and 
the acid itself will be spattered about. 

CMC 



Ignition — Lecture I Page 6 

Specific Gravity 

The weight of a liquid as compared with distilled water is known as its 
specific gravity. Distilled water at 60 degrees Fahrenheit is one, or unity. 
Liquids heavier than distilled water have a gravity greater than unity; 
lighter liquids such as gasoline have a gravity less than that of distilled water. 
Concentrated sulphuric acid is a heavy oily liquid, having a specific gravity of 
about 1.275. This, however, is the specific gravity of the electrolyte only when 
the battery is fully charged. The gravity of the electrolyte affords the most 
certain indication of the condition of the battery at any time. 

The Action of the Cell on Charge 

When the elements described are immersed in a jar of electrolyte of the 
proper gravity, and terminals are provided for connecting to the outside cir- 
cuit, the cell is complete. As the lead plate storage battery produces current 
at a potential of but two volts per cell, a single cell is l'arely used. The 
lowest number of cells in practical use is the three cell unit of the six volt 
battery, the different cells being permanently connected together by heavy 
lead straps, while detachable terminals are provided for connecting the bat- 
tery to an outside circuit. When the charging current is sent through the cell, 
the action is as follows: the sulphuric acid used in making the active material 
is forced out of the plates into the electrolyte, thus raising the specific gravity 
of the electrolyte. When practically all of this acid has been transferred from 
the plates to the solution, the cell is said to be fully charged and should then 
show gravity of approximately 1.300. The foregoing refers to the initial 
charge. After the cell has once been discharged, the active material of both 
groups of pates has been converted into lead sulphate. The action on charge 
then consists of driving the acid out of the plates and at the same time recon- 
verting the lead sulphate to peroxide of lead in the positive plate, and into 
spongy metallic lead in the negative plate. 

The Action of Cell on Discharge 

The action of the cell on discharge consists of a reversal of the process just 
described. The acid which has been forced out of the plate into the electrolyte 
by the charging current again combines with the active material of the plate 
when the cell is connected for discharge to produce current. When the sul- 
phuric acid in the electrolyte combines with the lead of the active material, 
lead sulphate is formed at both plates. This lead sulphate is formed in the 
same way that sulphuric acid dropped on the copper wire terminals forms 
copper sulphate, or, on the iron work of the car forms iron sulphate. In cases 
of this kind, it will always be noticed that the amount of sulphate formed is 
out of all proportion to the quantity of metal eaten away. In the same man- 
ner, when the sulphuric acid of the electrolyte combines with the lead in the 
plates to form lead sulphate, the volume is such as to completely fill the pores 
of the active material when the cell is completely discharged. This makes it 
difficult for the charging current to reach all parts of the active material, and 
accounts for the manufacturer's instructions never to discharge the battery 
below a certain point. 

As the discharge progresses, the electrolyte becomes weaker by the amount 
of acid that is absorbed by the active material of the plate in the formation of 
lead sulphate, which is a compound of acid and lead. This lead sulphate con- 
tinues to increase in bulk, filling the pores of the plates, and as these pores 

CMC 



Ignition — Lecture I Page 7 

are stopped up by the sulphate, the free circulation of the acid is retarded. 
Since the acid cannot reach the active material of the plate fast enough to 
maintain the normal action, the battery becomes less active, which is indicated 
by a rapid falling off in the voltage. Starting at slightly over two volts per 
cell, when fully charged, this voltage will be maintained at normal discharge 
rates with but a slight drop until the lead sulphate begins to fill the plate. 
As this occurs, the voltage gradually drops to 1.8 volts per cell, and from that 
point on will drop very rapidly. A voltage of 1.7 per cell indicates prac- 
tically complete discharge or that the plates of the cell are filled with lead 
sulphate and that the bat'teries should be placed on charge immediately. 

During the normal discharge, the amount of acid used from the electrolyte 
will cause the gravity of the solution to drop from 100 to 150 points, so that 
if the hydrometer showed a reading of 1.280 when the cell was fully charged, 
it will indicate but 1.130 to 1.180 when it is exhausted or completely dis- 
charged. The electrolyte then is very weak; in fact, it is a little more than 
pure water. Practically all of the available acid has been combined with 
active material of the plates. Toward the end of the discharge, the electro- 
lyte becomes so weak that it is no longer capable of producing current at a 
rate sufficient for any practical purpose. 

Capacity of a Battery 

The amount of current that a cell will produce on discharge is known as its 
capacity, and is measured in ampere hours. It is impossible to discharge from 
the cell as much current as was needed to charge it, the efficiency of the 
average cell of modern type when in good condition being 80 to 85%, or 
possibly a little higher when at its best, which is after five or six discharges. 
In other words if 100 ampere hours are required to charge a battery, only 80 
to 85 ampere hours can be discharged from it. This ampere hour capacity of 
the cell depends upon the area of the plate and the number of plates in the 
cell. 

The capacity of the cell as thus expressed in ampere hours is based on its 
normal discharge rate or on a lower rate, for example: Take a hundred am- 
pere hour battery; such a battery will produce current at the rate of one am- 
pere for practically one hundred hours, two amperes for fifty hours, or five 
amperes for twenty hours, but as the discharge rate is increased beyond a 
certain point, the capacity of the battery falls off. The battery in question 
would not produce 50 amoere^ of curre \t for two hours. This is because of 
the fact that the heavy discharge produces lead sulphate so rapidly and in 
such large quantities that it quickly fills the pores of the active material, and 
prevents further access of the acid to it, thus while it will not produce 50 
amperes of current for two hours on continuous discharge, it will be capable 
of a discharge as great or greater than this by considerable if allowed periods 
of rest between. With an open circuit the storage battery recuperates very 
rapidly. It is for this reason that when trying to start, the switch should 
never be kept closed for more than a few seconds at a time. Ten trials of 
ten seconds each with a half minute interval between them will exhaust the 
battery less than will spinning the motor steadily for a minute and forty 
seconds. 

The magnetism from a horse-shoe magnet, is called natural or permanent 
magnetism, but magnetism may be produced by passing a current through a 
coil of wire wound around a soft iron core. The core is magnetied, one end 
being the North and the other the South pole. As soon as the current stops, 

CMC 



Ignition — Lecture I Page 8 

the magnetism ceases. Thus an "Electro-Magnet" is a magnet only while the 
current is being passed through the coil of wire around the iron core. It has 
just been shown that the current flowing through a coil of wire affects the 
iron bar within it, so as to make the bar become a magnet. These same 
lines of force that will make a magnet out of a piece of soft iron will set up 
another current of electricity in another wire close to it, but which has no 
electrical connection with it, that is, if we make a coil of wire and attach the 
end of a coil to a battery and then wind another coil around the first one and 
insulate it from the first, we will find that every time the current in the first 
coil (the primary connected with the battery), is started or stopped (made 
or broken), there is a current set up or induced in the other, or secondary 
coil. As long as the current in the primary coil continues without change or 
interruption, there will be no current induced in the secondary winding. The 
current is produced in the secondary winding only when the flow of current 
in the primary winding is started or stopped. The effect of the primary coil 
upon the secondary has been found to be increased by placing a soft iron bar 
inside the two coils. 

The iwimary winding, as has been noted before, has only about one hundred 
turns of coarse insulated wire, but the secondary winding usually has several 
thousand turns of very fine wire. The greater the number of turns of wire 
in the secondary winding, the higher the voltage. Thus if a current of six 
volts is passed through, an induction coil which has about one hundred turns 
of wire in the primary winding and about 10,000 turns in the secondary wind- 
ing, a current with a pressure of approximately 8,000 volts, but practically 
no amperage, will be induced in the secondary winding. 

As the secondary current only flows when the primary current begins to 
flow and is suddenly interrupted, some device must be introduced, which will 
accomplish this. An "Interrupter" which may be either an electro-magnetic 
"vibrator" or a mechanical circuit-breaker may be used. The vibrator type 
is practically confined to use on the Ford car and will not be described at length. 
Its action is exactly like that of an electric door bell. The mechanical inter- 
rupter is used on all low and high tension magnetos and on all battery systems, 
such as the Delco. In a magneto, this "contact-breaker" is carried on the 
end of the armature shaft. 

The explanation of how the secondary high tension current has been gen- 
erated has been given, and it now only remains to be explained how this high 
tension current is distributed to the four spark plugs of a four cylinder engine 
in succession. 



CMC 



Ignition — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
IGNITION SECTION 

LECTURE II 

Magnetos 

The high tension magneto combines all the elements of a complete ignition 
system. It performs three separate operations as follows: It generates a 
low tension current; it transforms the low tension current into a high tension 
current; and it distributes the high tension current to the spark plug*. The 
high tension magneto differs from the low tension in only a few particulars. 

The armature on a high tension magneto has not only the primary winding 
but also another winding, consisting of several thousand turns of very fine 
wire wound around the outside of the primary winding, and insulated from it. 
As the primary current is interrupted by the breaker points a high tension 
current is induced in this secondary winding. The secondary current is con- 
ducted from the winding through an insulated ring on the armature to a car- 
bon brush and from there to the central point of the distributor. The rest 
of the magneto is essentially the same as has been described in the preceding 
lecture. 

Two features are included in the High Tension magneto, however, which 
do not appear in the Low Tension, but which are found on many induction 
coils. These are the condenser and the safety spark gap. 

When the two contact points of the "breaker" are suddenly separated there 
is a tendency for the primary current to continue to flow across the gap. This 
would cause a hot spark to be formed between the points which would not 
only burn the points away rapidly but would also prevent a rapid cessation 
of the current. As the primary current must be broken suddenly in order 
to get a strong secondary current, a condenser is used to overcome this ten- 
dency to flash across the points. In the Bosch magneto the condenser is 
placed in the hollow of the armature end cover at the circuit breaker end. 
This condenser consists of two sets of tinfoil sheets, the sheets of opposite 
sets alternating with one another. They are separated by sheets of mica to 
insulate them from each other. All the sheets of each set are metallically 
connected to the conductor leading from the primary winding to the station- 
ary breaker points, while the other set is grounded. In other words, the con- 
denser is "shunted" across the preaker points. The action of the condenser 
is to absorb the excess current that tends to flow or spark across the points 
after they are separated. 

The safety spark gap is practically a safety valve for the high tension cur- 
rent. It consists simply of two copper points with a rather wide gap. (Con- 
siderably wider than a spark plug gap) between them. One of these points 
is connected to the high tension or secondary circuit and the other to the 
ground. If one or more of the wires in the secondary circuit becomes de- 
tached, such as a wire to a spark plug, and the secondary current has no place 

CMC 



Ignition — Lecture II Page 2 

to go, it will jump across the points of the safety spark gap, to the ground 
instead of jumping through the armature and burning it out as it probably 
would if no outlet were provided for it. 

It is necessary to be able to stop the magneto from producing sparks when 
it is desired to stop the engine. For this purpose a sheet metal strip is pro- 
vided which makes contact with the stationary contact point in the circuit 
breaker and leads to a binding post on the circuit breaker housing. From 
this binding post a wire goes to a switch on the "dash." One side of this 
switch is grounded. When the switch is closed, the primary current flows from 
the stationary contact point, through the metal strip, binding post and wire, 
through the switch to the ground. In other words, the breaker points are 
"cut-out" and the primary current is allowed to flow to the ground unbroken. 
Consequently, no secondary current is induced and there is no spark at the 
plugs. 

The combustion should take place as the piston is on top of the compression 
stroke because at that point the gas drawn into the cylinder has been forced 
up into the head of the cylinder and is at the point of greatest compression — 
hence more force will be exerted on the head of the piston when the explosion 
occurs. If the explosion occurs after the pinion has started down the pressure 
is not so great. If the engine is running slowly, the explosion occurring be- 
fore the top of the stroke, will cause the force to be exerted against the piston 
travel, and will cause knock and loss of power. 

As gasoline vapor requires a fraction of a second in which to explode, there 
is a difference of time between the time the spark is made at the spark plug 
and the time the combustion of the gas actually takes place. If combustion 
took place immediately, when the spark occurred, then the proper time to set 
the spark would be on top of the compression stroke, but on account of the 
rapidity of the piston strokes, we must make allowance for the time necessary 
for the gasoline vapor to expand, and cause the spark to occur a fraction of 
a second early in order to have combustion take place exactly on top of the 
compression stroke. Setting the time of spark to occur before the top of the 
compression stroke is called "advancing" the spark. Setting it to occur ex- 
actly on top or a little after the top is called "retarding" the spark. It will 
be understood that when the engine is running slowly the spark should occur 
in the retarded position, but when running at high speed in the advanced 
position. 

In order to control the position or time of the spark with relation to the 
stroke of the piston, the circuit breaker housing is so arranged that it can be 
rocked around its axle, being provided with a lever arm for the purpose, from 
which connection can be made to a spark lever on the steering post. It will 
be clear that if the armature shaft turns right handed and the circuit breaker 
housing is moved to a certain angle in a right hand direction, the cam will 
raise the movable breaker point later with relation to the position of the en- 
gine crank shaft; while if it is moved in a left hand direction the breaker 
point will open earlier. In this way the point at which the spark occurs can 
be shifted through an angle of about 35 degrees. 

In general it is customary in installing a magneto to set the spark at full 
retard with the piston at the top of the compression stroke and the operation 
is accomplished as follows: 

By sticking a long piece of wire through the pet cock of No. 1 cylinder and 
turning the engine over by hand, the highest point of the stroke may be noted. 
Both exhaust and inlet valves will be closed. Turn the breaker box housing 
on the magneto to the full retard position. Then revolve the armature to the 

CMC 



Ignition — Lecture II Page 3 

point where the distributor brush is making contact with the terminal leading 
to No. 1 spark plug and the breaker cam is just beginning to separate the 
points, then either connect the magneto to the shaft or mesh the timing gears 
as the case may be. Instructions of different manufacturers will vary in this 
point. 

The spark is usually advanced or retarded by means of a hand lever on the 
steering column, but it may be automatically advanced and retarded as in the 
Eisemann mangneto. The spark is automatically advanced as the speed of 
the engine increases by means of a sort of governor on the armature shaft 
which rotates the breaker housing just as if it were done by hand. This is 
called a "set" spark. 

If no spark occurs at the plug the magneto trouble may be : 

1. In the breaker box 

(a) Breaker bar spring weak or broken or bar stuck. 

(b) Points too far apart or too close. 

(c) Points badly burned or pitted. 

(d) Short circuit in primary current. 

2. In the distributor 

(a) Distributor brush not rotating. 

(b) Distributor brush broken or stuck. 

(c) Distributor brush oil-soaked or glazed. 

(d) Short circuit in distributor box. 

3. The magnetism may be weak in the magnets. 

Naturally, before looking for these various troubles it should be ascertained 
that all wires have tight connections and are not broken. 

If the breaker points have too small or too wide a gap they may be ad- 
justed by means of a small wrench and gauge provided by the manufacturer. 
If they are dirty or sticking, they should be cleaned by means of a strip of 
fine emery cloth or a watchmaker's file in order to have a perfectly flat, smooth 
surface. In case the magnets are demagnetized, they should be turned over 
to the electrician for re-charging. When a magnet is fully charged it should 
lift an iron weight of about ten to fifteen pounds. The magnet is re-charged by 
placing it on the poles of an electro-magnet, North pole of magnet to South 
pole of electro-magnet. This operation requires usually about one minute. 

All the foregoing has been description of the armature type of magneto. 
The Dixie magneto as used on Liberty trucks is of another type known as the 
inductor type. The general principles of this type are the same, but the ro- 
tating element simply has two cast iron inductors which revolve past a sta- 
tionary armature winding. 

The advantages of this type of magneto, as claimed by the manufacturer, 
are as follows: As the contact breaker box is attached to the mounting of 
the coil, the latter moves with it when the former is partly rotated to advance 
or retard the occurrence of the spark in the cylinders, so that the opening of 
the contact points always takes place at the point of maximum current. An 
absolute advance of thirty degrees or more is obtained by simply rotating the 
coil carrying structure to which the breaker box is attached around the axis 
of the rotating pole pieces. 

Inasmuch as the only rotating elements of the Dixie magneto are the two 
pole pieces there are no rotating wires to cause trouble by becoming loose. 
Another great difference between the Mason principle on which the Dixie 
operates and the armature type is in the fact that the rotating poles in the 
Dixie do not reverse their polarity at any time, consequently the lag due 
to the magnetic reluctance in this part is eliminated. 

CMC 



Ignition — Lecture HI Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
IGNITION SECTION 

LECTURE III 

Battery Ignition 

In the discussion of battery ignition the Delco system will be used to illus- 
trate the general principles as the basic principles of all other battery igni- 
tion. Systems are practically the same. 

The principal parts of a battery ignition system are a distributor and timer, 
ignition or high tension coil, spark plugs and wiring, the current being fur- 
nished by the battery and generator. The circuit breaker, ammeter, auto- 
matic spark advance and combination switch are units that are essential to 
the perfect operation of the system but cannot be included in the list of prin- 
cipal parts. 

In the Delco, as well as in other types of battery ignition systems, the bat- 
tery is the primary source of electrical current. However, the generator and 
storage battery are so wired that, when the amount of current generated by 
the generator is greater than that generated by the storage battery, the cur- 
rent from the generator not only charges the storage battery, but is used as 
the source of electrical current for ignition. Therefore the voltage of the 
primary ignition circuit never falls below the voltage of the storage battery 
no matter what the speed of the generator may be, and as the voltage or 
charging rate is regulated in the generator it never reaches a higher voltage 
than would be destructive to the ignition system. 

The electrical current which is furnished by the battery and generator is 
a primary current, so it is necessary to "step it up" to a much higher voltage 
in order that it will make a spark at the spark plugs. This is accomplished by 
an ignition or high tension coil, which has been fully explained in a preceding 
lecture. The only part of the coil that need be considered here is the addi- 
tion of a resistance unit that is installed with the coil. The purpose of this 
resistance unit is to obtain a more nearly uniform current through the pri- 
mary windings of the coil at the time the contact points open. It consists of 
a number of turns of iron wire, the resistance of which is considerably more 
than the resistance of the primary windings of the ignition coil. If the ig- 
nition resistance unit were not in the circuit and the coil was so constructed 
as to give the proper spark at high speeds, the primary current at low speeds 
would be several times its normal volume with serious results to the timer 
contacts. At low speed the resistance of the unit increase due to the slight 
increase of current heating the resistance wire. 

The timer or interrupter in the Delco system is mounted directly under the 
distributor and is driven by the same shaft. Its purpose is the same as in 
the high tension magneto ; to open and close the primary circuit and by doing 
so to induce a secondary current in the secondary winding of the high tension 
coil. 

CMC 



Ignition — Lecture III Page 2 

From the high tension coil the current is carried to the rotor of the dis- 
tributor and there distributed to the various spark plugs. In the end of the 
rotor arm will be found a rotor or contact button which is held in contact with 
the distributor head by a spring and as it revolves makes contact with the 
terminals leading to the spark plugs. The distributor head itself may cause 
trouble if the track over which the rotor operates gets sufficiently dirty to 
carbonize so that the spark jumps across one terminal to another and causes 
premature ignition. The most satisfactory test for this trouble is to replace 
the head with another head of similar model and note the effect upon the ig- 
nition. The track of the distributor head should be kept clean with a rag 
slightly moistened with gasoline, so as to keep it polished and prevent the 
rotor button from sticking and thus cutting a track. If a track is cut, the 
rotor button should be inspected to see if it is properly seating and that the 
spring tension is not too great. 

The ammeter is located on the dash of an automobile. Its purpose is to 
indicate the current that is going to or coming from the storage battery. 
When the engine is not running and the current is being used for the lights, 
the ammeter shows the amount of current that is being used and the ammeter 
hands point to the discharge side, as the current is being discharged from the 
battery. When the engine is running about generating speed and no current 
is being used for lights or horn, the ammeter will show the charge. This is 
the amount of current that is being charged into the battery. However, on 
some systems, such as the Westinghouse as used on the Pierce-Arrow, the 
ammeter will show very little charge if the battery is nearly at full charge, 
while, if the battery is low, the ammeter hand will indicate a heavy charge. 
Therefore, if the ammeter does not show a heavy charging rate from the gen- 
erator, the conclusion must not be reached that the generator is not properly 
operating. A hydrometer test should be made of the battery in this instance. 

The automatic spark advance is a feature that has been brought out by 
several manufacturers of battery ignition systems. In the Delco system it 
consists of a set of weights. The weights are operated on an advance ring 
and so by changing the position of the sleeve with regard to the distributor 
shaft proper, in a manner very similar to the operation of a manual advance 
ring, they advance or retard the fibre timing cam according to the position 
of the automatic weights. The operation of these weights is also similar to 
that of the governor on a steam engine. 

To time the ignition of the Delco system the adjustment screw is loosened, 
which allows the cam to move with respect to the shaft upon which it is 
mounted. Turning the cam in a clock-wise direction, or towards the right, 
advances the time of ignition, and counter-clockwise retards it. Top dead 
center, of the compression stroke, or slightly before top dead center, is found 
in cylinder number one and the cam to which the rotor is attached is moved 
on the shaft until the rotor is making contact with the terminal in the dis- 
tributor head marked number one. The timing adjustment screw is then 
screwed down firmly in place. The proper timing of the remaining cylinders 
is automatically taken care of by the positive design of the ignition system. 
It is most important that the timing adjustment screw be absolutely tight, 
otherwise the cam would soon slip out of place when the motor is running 
and so cause untimely ignition. 

The common practice, upon discovering a defective spark plug, is to simply 
replace it. This in fact is the only way of procedure in case of spark plug 
ti'ouble, but many things can be done to aid in the prevention of spark plug 
deterioration. 

CMC 



Ignition — Lecture HI Page 3 

The adjustment of the spark gap, or clearance between the two points of 
the spark plug is essential to correct ignition. This gap should be about .025 
of an inch. Nearly all manufacturers of ignition systems furnish a gauge to 
properly set the spark, and one of these should be in the possession of the 
mechanic. 

The development of the spark plug manufacture has been a long and tedious 
one, it being necessary for the spark plug manufacturer to keep pace with the 
rapid developments of the automobile motor. The Cadillac and Winton were 
the first to make a spark plug, but it was never satisfactory due to the fact 
that it had a tendency to absorb oil which soon rendered it useless as it de- 
stroyed the insulating properties of the porcelain allowing the high tension 
current to leak through the shell. 

The best material for the manufacturer of spark plugs is universally con- 
ceded to be porcelain. The ingredients to enter into the manufacture of this 
porcelain are collected from all parts of the world. It consists of Kaolin, 
Flint, Felspar and ball clay which are brought together and mixed in the 
proper proportions and then fired at the right heat in the same way that steel 
is given a heat treatment. 

The best porcelain is the one which has the least amount of leakage of 
electrical current, but there is no porcelain made which has not a point at 
which it breaks down. It must be remembered that in a cylinder which is 
firing with too rich a mixture, a veritable furnace exists, and this soon has 
its effect on the porcelain of the plug. All the porcelains used in the manu- 
facture of spark plugs are what are known as soft porcelains and these will 
absorb both carbon and water. When carbon is absorbed the porcelain is 
transformed in its internal structure and the leakage through the insulator 
increases. It therefore is the duty of the mechanic, in order to protect the 
spark plugs, to see that too rich a. mixture is not used and to keep the carbon 
well cleaned from the motor. Experiments have shown that a temperature 
of 1350 degrees Fahr., is reached within an internal combustion engine even 
when it is operating properly. 

Spark plug terminals should be examined at frequent intervals to see that 
they are tight. The spark plug itself should be properly gasketed and firmly 
screwed down in the cylinder head to prevent any loss of compression. The 
terminals and plugs should also be kept clean and free from all grease and oil. 

The size wire to use depends upon the amount of current that must flow 
through it and the length of the wire. The longer the wire the greater the 
resistance offered to the flow of current. Therefore, there will be too much 
drop in the voltage at the wire terminal if it is not of sufficient size. The 
conductor must be large enough to carry the required amount of voltage to a 
given point with less than 4 % drop. 

Nearly all automobiles are using a single wire system and the length of the 
wire is seldom more than ten or twelve feet. Primary wire is used for low 
tension, or voltage, as ignition, from the battery to the coil and from the coil 
to the timer, or for lights. It is usually flexible, consisting of several strands 
of wire. When used for lighting it can be "duplex" or even consist of four 
wires together and is usually encased in metal armor for protection. Sec- 
ondary cable is used for high tension ignition currents. The wire is small 
but heavily insulated. Starting motor wire is very heavy, being several times 
the size of the secondary cable, but not so heavily insulated. Wire of this 
kind is used because it does not carry a high voltage, only 6 to 24 volts, 
whereas the secondary cable carries a voltage high enough to jump a gap. 

CMC 






Ignition — Lecture HI Page 4 

The stai'ting motor wire carries a large amperage or quality of current. 
For instance, the wire running from the ostrage battery to the starting motor, 
when first starting, must carry from 80 to sometimes 400 amperes, according 
to the size of the motor. This is only for a few seconds, but large wires must 
necessarily be used to carry this great quantity, even for such a short time. 
The wires running from the generator to the storage battery are much 
smaller, as the quantity of current which passes through them is only 5 to 
25 amperes. 

As a comparison, imagine water pipes. If it were desired to pass 150 gal- 
lons of water through a pipe in one hour it would require a much larger pipe 
than it would if but 25 gallons were to flow through it in the same length 
of time. 

The following table of the sizes of wire to be used in making different con- 
nections should be carefully studied by the mechanic: 

Generator to Battery No. 10 

Battery to Starter No. 1 or 2 

Headlights No. 12 or 14 

Tail Light No. 14 

Ignition (Primary) No. 14 

Ignition (Secondary) No. 14 or 16 

Horn No. 18 

The highest numbers indicate the smallest wire. The size wires given above 
are determined by B and S gauge, which means Brown and Sharp gauge, and 
which is recognized as standard. 

The connection in electrical wiring should be soldered. The unsoldered 
connections may work as well as soldered connections at the time of being 
made, but the resistance always increases. In placing a wire terminal under 
a terminal nut, as on a spark plug, twist the wire in the direction that the nut 
turns. When connecting a wire under a nut a copper or brass washer should 
be used. 

Wiring troubles are numerous if the wiring is not properly done. Oil and 
grease destroy the insulation, so the wires should be kept as free from this 
as possible. Moving parts of the motor or car must not touch the wires. Pro- 
tect the wires from chafing. Avoid frayed ends. Tape all connections made 
in the wire. Connections must be tight as well as all terminals. These should 
be inspected, for vibration often jars them loose. A common trouble is one 
where connections of wire terminals to the storage battery and ground con- 
nections to the frame are not properly made. Cable should be used where 
the wire must make a sharp turn, as vibration from the motor is apt to cause 
a break in the solid wire. 



CMC 



Ignition — Lecture IV Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
IGNITION SECTION 

LECTURE IV 

Generators 

In order that battery ignition might be practical it was necessary that the 
manufacturers of electrical equipment devise some method by which the stor- 
age battery could be kept in a charged state while it was in use. This was 
accomplished by the installation of a generator. 

Prior to the advent of the electrical starting and lighting systems, the mag- 
neto had reached a degree of development that appeared to leave not the 
slightest doubt as to its representing the ultimate type of the ignition current 
generator. With the installation of direct current generators capable of sup- 
plying more than enough current for starting and lighting the car and charg- 
ing the storage battery, it seemed that there was a duplication of electrical 
apparatus. In other words, it was asked: "With such an ample and reliable 
source of current on the car as the charging generator and storage battery, 
why continue the use of the magneto?" The installation of a generator in 
connection with the use of a storage battery and battery ignition makes it 
necessary to briefly consider the principles and construction of the generator 
or dynamo. 

A dynamo consists of two main parts (1) the means of producing the 
strong magnetic field known as the field magnets and (2) a series of con- 
ductors in which the currents are generated by induction, called the armature. 
One of the parts must be capable of rotation relative to the other. A current 
so produced is called an alternating current and the machine producing it is 
called an alternating current generator or "magneto" which has been ex- 
plained in detail in a preceding lecture. 

A direct current machine is fitted with a short cylinder called a commutator, 
made of a number of metallic segments insulated from each other, to which 
equidistant conductors of the armature are joined. The two brushes are 
placed so as to rub on opposite segments (for a two pole machine) of this ar- 
rangement so that the armature of the machine can be rotated while the 
brushes remain fixed and make contact with the segments as they rotate. The 
brushes are arranged so that just as the current is reversed in the conductor, 
the segment attached to that conductor is under the brush. The current will 
be continuous in one direction. This is the type of machine found on all auto- 
mobile lighting and ignition systems in use at the present time. 

Tbe principal parts of a generator are (1) the armature, in which current 
is generated (2) the field cores or magnets, either permanent, which is the 
horse-shoe magnet as used in the magneto, or electro-magnet, which is only a 
magnet when a current of electricity is passing through it (3) the pole pieces 
(4) commutator (5) brushes, either metallic or carbon and (6) regulation of 
current output. 

Due to the fact that the current generated by a dynamo increases with the 
speed of the revolving armature, it is necessary to make some provision by 
which the flow of current can be regulated. This is known as regulating the 

CMC 



Ignition — Lecture IV Page 2 

charging rate, and unless the charging rate be properly regulated there is dan- 
ger of overcharging the battery. Overcharging the storage battery is indicated 
by the rapid evaporation of the water and the unnatural heating of battery. 

There are two types of current regulators (1) the third brush type, as used 
by the Delco and (2) the vibrating type of regulator, as used by the Westing- 
house. There are two arrangements of the Delco third brush; one under the 
commutator and one over the commutator. In the first, the third brush is sup- 
ported on an arm which is arranged to lengthen or shorten by means of a 
screw and slot in the arm. The moving of this brush in the direction of rota- 
tion increases the charging rate and moving the brush in the opposite direc- 
tion, of course, decreases the charging rate. The generators leave the factory 
adjusted to give an ample charging rate at maximum generator speeds. 

If the car is driven a great deal and the lights and starter used compara- 
tively little it is possible to overcharge the storage battery unless the charging 
rate is decreased. If it becomes necessary to regulate the charging rate, the 
third brush will, of course, have to be moved. At any time that the brush is 
moved it is absolutely essential that a piece of fine sand paper, with the sand 
side next to the brush, be drawn between the brush and the commutator. If 
this is not done the brush will not take good contact and the charging rate will 
not be so high as when the brush is well seated. When the charging rate is 
increased or decreased it is always essential that it be carefully checked up by 
the use of the ammeter on the combination switch which is usually located on 
the dash. In no case should the ammeter show more than 20 amperes. Check- 
ing of the charging rate should be made after the brush is correctly seated 
and the engine is gradually speeded up. The test should be made with all the 
lights turned off. 

It will be found that the third brush that is mounted over the commutator 
is held in a brush arm that is made in two pieces. The part to which the 
brush is fastened has a slot through which passes two screws, attaching it to 
the other part. By loosening these screws it is possible to slide one part upon 
the other and so increase or decrease the length of the arm. When the arm is 
shortened the charging rate is decreased and when it is lengthened the charg- 
ing rate is increased. 

The vibrating type of regulator as used on the Westinghouse generator is a 
mechanical regulator, being operated by the cam. Two silver contact points 
are made to vibrate by this cam and by their opening and closing alternately cut 
in and out a resistance unit. The greater the speed of the generator, the more 
rapid is the vibration of the two points and the more often is the resistance 
unit cut into the circuit, thus maintaining constant the output of the current 
or sustaining a given charging rate. This vibrating device is held in contact 
with the cam by spring tension and the increasing or decreasing of this spring 
tension regulates the charging rate. 

To adjust the regulator a few rules should be strictly followed. Be sure 
that the fibre rests evenly on the cam and does not change its position when the 
pressure caused by the armature spring is removed. Be sure that the con- 
tacts line up properly and come together only at one point. Never file off the 
copper rivet on the regulator armature as it is used as a stop and should set 
.015 to .019" high. Set the high part of the cam under the fibre and screw 
the regulator core down until there is from .002 to .003" between the copper 
stop and the regulator core (use feeler gauge) and lock the core by means of 
the lock nut on top of the regulator. Set the proper voltage by the spring- 
tension-stop at the end of the armature spring to meet the test specifications 
of that particular machine. It is always well to wipe all oil and grease from 

CMC 



Ignition — Lecture IV Page 3 

the regulator parts before assembling and place a thin coating of clean vaseline 
on the sides and bottom of the fibre. When replacing regulator coils the correct 
style of coil must be used, as some other style may make it impossible to set 
the regulator. 

Aside from regulating of the charging rate there are a few things that the 
mechanic should know about the general care of a generator. Through the 
proper care of this unit expensive repair work can many times be prevented. 

Brush Care. — Once or twice a season the first coiled springs holding the 
brushes against the commutator should be raised and the brushes examined to 
see that they operate freely in their holders. Oil or dirt should be removed 
with a stiff bristle brush and gasoline. Faults in the brushes can be classified 
into five divisions — namely (1) grounded (2) poor spring tension (3) sticking 
in holder (4) poor fit to commutator surface and (5) over-heating holders. 
When grounded, it is due to defective insulation or dust deposit. When the 
spring tension fails, the brushes are worn too shoi't, which would necessitate 
replacement, the spring tension is not properly adjusted or has been thrown 
out due to heat, or the springs themselves may be broken. However, the 
brushes should never be allowed to wear down too short. When the brushes 
stick it may be due to binding or from dirt and grease. When the brushes do 
not fit the brush holders it is a matter of manufacture. Overheating of the 
brush holders is caused by sparking due to ill fitting brushes or brush lead 
connections. If there is any sparking, or if the commutator becomes dull, it 
is sure to be the result of brush holder springs being too loose, or due to ex- 
cessive vibration caused by bent shaft, an unbalanced gear pinion, or defective 
mounting. Always keep the brush spring away from the brush holder. 

Carbon dust (providing that carbon brushes are used) may be worked from 
the brushes by the commutator and deposited in the lower part of the gener- 
ator. This should be blown out with air as an excessive deposit may cause a 
ground. 

Commutator troubles can be divided into two heads: (1) those due to defective 
manufacture and (2) those due to surface wear or deteriorating in serving. 
Defective commutators may be grounded, have a short circuit between their 
segments or have loose segments and are generally denoted by sparking at the 
brushes. Those that have deteriorated in service show a rough or blackened 
surface due to the following causes: — sparking from worn or short brushes, 
sparking on account of high mica, cheap brushes, oil collecting on commutator 
surface, loose copper segments, poor contact between brushes and commutator 
or poor contact due to weak brush spring pressure. Commutators should be 
kept smooth. If blackened or rough they can be dressed with fine sand paper, 
while the armature is rotating. 

Sometimes a decided "squeak" will come in the generator, which is caused by 
glazed brushes. In order to eliminate this, the glazed surfaces must be rubbed 
down. Place a strip of sand paper between the brushes and the commutator 
with the sanded side of the paper against the brushes, turning the armature 
until the brushes are smooth and the glazed surface has been removed. Never 
use emery cloth. 

Between the commutator segments mica should not protrude. This can be 
dressed down on the lathe or in some instances filed down with a very fine cut 
file, but care must be taken that no small particles of copper are left bridging 
across the segments. This work must be done with armature removed and 
prefei-ably on a lathe. If the commutator is greasy wipe clean with a clean 
cloth but never use waste. 

CMC 



Ignition — Quiz Questions Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
IGNITION SECTION 

Quiz Qukstions 

1. At what time should the spark occur in the cylinder when the engine 
is cranked? 

2. When it is running? 

3. What is meant by advancing the spark? 

4. By retarding the spark? 

5. Why is it necessary to change the time at which the spark occurs? 

6. What is meant by automatic advance? 

7. Explain why more advance is required when an engine is running 
with nearly closed throttle and pulling a light load than when running at the 
same speed with wide-open throttle and pulling a heavy load? 

8. What is the symptom of too much advance? 

9. With a battery ignition system, where should the spark lever be set 
when the engine is cranked? 

10. Where with magneto ignition? 

11. What appearance does a spark plug have when removed from a cylin- 
der which has not been firing? 

12. How should it be cleaned? 

13. If it is separable and has been taken down, how should it be tested 
for compression leaks when assembled? 

14. How far apart should the points be spaced? 

15. How does this compare with the thickness of a dime? 

16. With the thickness of a United States postal card? 

17. With the thickness of a calling card? 

18. What will be the effect on the running of the engine if the gap is too 
large, and under what particular operating conditions? 

19. What if it is too close? 

20. What is the best method of testing a plug? 

21. Why may laying it out on the cylinder with wire attached prove an 
unsatisfactory method of testing? 

22. What should be used on the threads of a plug to make subsequent 
removal easy? 

23. Explain the difference between the different types of plug threads. 

24. How many are there? 

25. What may be the effect of using the pliers to tighten the binding nut 
on top of a plug? 

26. What effect does the intense heat developed during a long hard pull 
with wide-open throttle have on the insulation properties of porcelain? 

CMC 



Ignition — Quiz Questions Page 2 

27. Explain three methods of testing- to determine which cylinder of an 
engine is missing first? 

28. What causes other than ignition might cause the cylinder to miss? 

29. How can it be determined definitely that current capable of produc- 
ing a good hot spark is being supplied to the plug? 

30. How can the driver be sure that the plug in the missing cylinder is a 
good one? 

31. What other causes besides poor ignition may cause a cylinder to miss 
fire when the engine is running idle, even though the compression seems to 
be right when tested by hand crank? 

32. What is the special use of auxiliary spark gaps, often called intensi- 
fies, when the engine seems to miss irregularly? 

33. How many dry cells are needed to operate a battery system? 

34. What will be the result, if they become damp while connected up? 

35. How are they connected? 

36. What precaution should be taken to prevent their i*unning down when 
not in use? 

37. How should a storage battery be tested to determine whether it has 
enough "juice"? 

38. What will be the effect of dirty battery terminals? 

39. How are they to be kept from getting into this condition? 



CMC 



Trouble — Lecture I Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 

TROUBLE SECTION 

LECTURE I 

Engine Trouble 

Failure of the Engine to Start 

When an engine fails to start readily the cause may be found in most cases 
in a very short time if a regular system of search is followed, instead of the 
hit or miss method of looking first one place and then another, and tampering 
with first the carburetor, then the magneto, then the wires, and so on without 
any definite plan. 

If the engine is to be run it must take into its cylinders an explosive mix- 
ture of fuel and air, it must compress this mixture ; the mixture must be ig- 
nited by a good spark produced at the right time ; and the valves must so op- 
erate that the burned products are expelled from the cylinders properly to 
make room for new incoming mixture. 

A very good method to follow in testing or trouble hunting is: 

(1) Try the compression with the hand crank, turn the engine at least 
two revolutions and rock against each compression to determine that there 
are the proper number of compressions and that all are nearly equal. 

(2) Be certain of the fuel. The best way is to prime each cylinder di- 
rectly with a small amount of gasoline, being careful not to over prime — 
especially if the engine is hot. Gasoline must be in the cylinder to burn, and 
to put a small amount there is quicker and often more effective than tam- 
pering with the carburetor. 

(3) Investigate the spark. Disconnect a spark plug wire and hold the end 
a short distance from the plug, or disconnect the wire from the secondary 
terminal, while the engine is turned over and watch for the occurrence and 
quality of the spark. With all of these conditions right, the engine should 
start. If it still fails, continue with 4. 

(4) Be sure that the mixture is not too rich. If the engine is hot, it is 
very easy to have it flooded ; that is, to have such an excess of vaporized fuel 
in the cylinders that no explosion will take place. Cranking the engine slowly 
with the priming cups slightly open, or with the throttle wide open and the 
fuel supply turned off should remedy this condition. Sometimes flooding 
washes the oil away from the piston and rings, and it becomes necessary to 
pour a small quantity of oil into each cylinder through the spark plug hole 
to seal the pistons and rings against leakage of compression. 

(5) Test the timing of the spark. Disconnect a spark plug wire and hold 
it near the plug or near a clean spot on the engine, or remove a spark plug 
and lay it on the cylinder with the wire attached. Then see if the spark occurs 
at the end of the compression strokes of the cylinder under inspection. The 
compression stroke may be found by holding the thumb over the open priming 
cup or spark plug hole. 

CMC 



Trouble — Lecture I Page 2 

To Test the High Tension Magneto 

If the car is equipped with high-tension magneto, disconnect the conductor 
which connects the collector brush to the centre of the distributor and turn 
this so a metal part of it is about a sixteenth of an inch from the magneto or 
some other metal part of the magneto or car, or turn the safety-gap cover 
spring until it is close to the magneto. If the construction does not permit 
this test, remove the distributor and fix or hold a wire with one end against 
some metal part of the magneto or of the engine and the other end near to, 
but not against the centre of the distributor arm, or use a test wire as seems 
best. If no spark is produced when the engine is cranked briskly, remove the 
primary or grounding wire which connects to the switch and spin again. If 
there is still no spark, examine the circuit breaker points while the engine is 
turned slowly in order to determine whether they break and make contact 
properly. A small mirror will make this examination easy. The points may 
be fouled or burned, they may be oily, or the breaker arm may be frozen fast 
so that the spring does not bring the points into proper contact after they 
have been separated by the cam. 

They should break approximately .015 of an inch or about as much as the 
thickness of a calling card. The wrench provided by the manufacturer for 
adjusting the points generally has a thickness gauge. 

I 

To Test a Battery Ignition System 

If the engine is equipped with a modern ignition distributor battery sys- 
tem, disconnect one end of the wire which joins the secondary terminal of 
the spark coil to the center of the distributor and hold the end close to, but 
not against, the terminal from which it was detached. Crank the engine and 
watch for the spark. The trouble of cranking can be avoided by varying the 
method of test. Loosen the clamping or lock springs and lift or turn and lift 
the distributor head. Fasten one end of test wire to ground and hold the 
other close to, but not against, the secondary terminal of the coil or close to 
the center terminal of the distributor while the distributor is laid or held in 
an inverted position. Cause the breaker points to make the break contact 
with the finger or a screw driver. If no spai-k is produced, use a test lamp or 
test wire to determine whether there is current at the primary terminals of 
the coil and at the terminals of the circuit breaker. The current should pass 
from the battery through the switch, through the primary of the coil, through 
the circuit breaker points, and back through the wire or through the frame to 
the battery. 

While the engine is turned, note whether the breaker points connect and 
break the circuit properly. The points may be fouled or burned, they may be 
oily, or the spring may not return the breaker arm so that the points make 
proper contact after they have been separated by the cam. The wrench pro- 
vided by the manufacturer for adjusting the points generally has a thickness 
gauge. 

Examine the inside of the distributor and the distributor arm and make 
sure that they are clean and dry. They may be wiped out with a clean cloth 
or with a cloth moistened with gasoline. If the distributor head is very dirty 
it can be cleaned with very fine sandpaper or with a little dust on a piece of 
damp cloth held over the end of the finger. 

CMC 



Trouble — Lecture I Page 3 

Testing of a Spark Plug 

In an effort to test a spark plug the driver often unscrews it from the cylin- 
der, reattaches the wire, lays it down on the cylinder casting, taking care that 
the terminal does not make contact, and watches for the occurrence of the 
spark while the engine is turned over. The failure of the spark to occur in 
the plug if one can be obtained from the end of the detached wire is good 
evidence that the plug is out of order. The occurrence of the spark in the 
open air is, however, no indication that one will occur under high pressure 
when the plug has been screwed back into the cylinder. 

Whether the spark plug has been firing properly or not can generally be 
determined by inspection as a plug which has been missing is liable to present 
an oily or sooty appearance, instead of a dry, yellowish-white, clear appear- 
ance which indicates that the cylinder is firing properly. 

Probably one of the most satisfactory methods of testing is to try the un- 
satisfactory plug in a cylinder which is known to have been operating prop- 
erly, or to try a spark plug which is known to be good in the troublesome 
cylinder. 

To determine which cylinder is missing fire, the plugs may be short circuited 
one or more at a time with a screw driver or other suitable instrument, or 
the wires may be detached from the spark plugs, one or more at a time. The 
priming cups may be opened and the issuing flame watched for, or the sound 
noted to determine whether there is any change in sound when the plug is 
short circuited or the wire detached. 

Engine Trouble Charts 

The study of a trouble chart which lists all of the possible causes or certain 
general troubles or symptoms of trouble which may occur with an engine is 
recommended. Such charts are sometimes provided in the manufacturers' 
instruction books or furnished with advertising literature. 



CMC 



Trouble — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
TROUBLE SECTION 

LECTURE II 

Test Questions 

1. State order of procedure in identifying cause of failure of engine to 
start, or of starting an engine which fails to start readily. 

2. If engine has been running properly and dies out with a popping back, 
what is likely to be the cause? 

3. If engine is warm and refuses to start, even when primed well and 
when the choke or primer has been used and there is a good spark, what is 
likely to be the trouble? 

4. What should be done to remedy the cause? 

5. If an engine hits all right except when running idle and then it is 
always the same cylinder which misses, what are some of the possible causes? 

6. How should a test be made for each cause? 

7. What is the purpose of spark gaps in locating trouble? 

8. If the carburetor adjustment is suspected, what should be done before 
the adjusting devices are tampered with or changed? 

9. If the engine runs well idle and when pulling slowly; or, at light load, 
it gains speed or accelerates readily but dies out and pops, what trouble is 
indicated? 

10. What is a temporary remedy? 

11. The permanent remedy? 

12. If the engine lacks power and the radiator boils, what may be the 
cause? 

13. If the engine kicks when cranked, what trouble is to be suspected? 

14. If the engine will not pull and there is poor compression in all cylin- 
ders, what may the trouble be? 

15. Name the causes which might be responsible for missing on one 
cylinder only. 

16. What is the purpose of a governor? 

17. What part or accessory of the engine is controlled by the governor? 

18. When does it come into action? 

19. How can the driver tell whether the governor is working? 

20. If it is not working or has been disconnected, what should be done? 

21. When? 

22. What is the result of running an engine at a high rate of speed with- 
out any load? 

23. If a governor-controlled throttle remains shut and prevents operation, 
what should be done? 

CMC 



Trouble — Lecture II Page 2 

24. How is a governor generally arranged to make tampering uniikeiy? 

25. What is the purpose of a muffler or silencer? 

26. What is the effect when it becomes obstructed? 

27. What is the cause of muffler explosions? 

28. When a car is coasting down hill, what precaution may be taken to 
prevent muffler explosions? 

29. What is the purpose of a cut-out valve? 

30. How much increase in power is there under ordinary running con- 
ditions over an efficient muffler? 



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Trouble — Lecture III Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
TROUBLE SECTION 

LECTURE III 

General review of all foregoing: 

Student is given vehicle with various sorts of trouble, or out of adjustment 
and required to put it in operation on the basis of the work that he has done 
previously in the course. 

The following are a few troubles that can be found on a car: 

1. Broken spark plugs. 

2. Loosened valve tappet. 

3. Breaker points out of adjustment. 

4. Spark plug electrodes set too far or too near. 

5. Tie-rod lengthened to make front wheels toe-in. 

6. Ground wire off. 

7. Carburetor float out of adjustment. 

8. Gear shifting controls set wrong. 

9. Collector brush removed on magneto. 

10. Internal brakes dragging. 

11. Distributor segments connected together by lead pencil marks. 

12. Coil vibrators out of adjustment. 

13. Ignition switch terminals changed about. 

14. Spark plug wires changed about on the distributor. 

15. Clutch adjusted so as not to disengage engine from the transmission. 



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Carburetor — Lecture I 



Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 

CARBURETOR SECTION 

LECTURE I 

The Carburetor 

Some knowledge of the proportions of the liquid commonly sold as gasoline 
will help the understanding of carburetors and of carburetor and engine per- 
formance. If a spark plug with two wires attached is suspended in a large- 
mouthed bottle filled almost to the top with gasoline, a continuous series of 
sparks can be produced without igniting it. If a few drops of gasoline are 
shaken in a glass bottle and a spark is produced or a lighted match is held 
at the neck of the bottle a sudden flame or explosion will occur. If a large 
mouthed bottle containing a small quantity of gasoline is placed upon an elec- 
tric hot plate or on an inverted flat iron and heated until the gasoline bolts 
freely, and a spark plug suspended where it is completely surrounded by the 
warm vapor sparks can be produced without causing any explosion. These tests 
demonstrate the fact that explosive mixtures must contain both air and the 
vapor fuel. An explosive mixture can be obtained without reducing the liquid 
to a clear, transparent vapor by breaking it up into a sufficiently fine spray, 
for example, like the spray from an atomizer. Even solid fuel if divided into 
very fine powder mixed with air may be explosive, as is shown by the fact that 
explosions sometimes occur in the dust laden air in a flour mill or in the coal 
bunkers in the hold of a ship. 

The purpose of the carburetor is to supply a mixture of a finely atomized 
spray or a vapor of gasoline (or other suitable fuel), and air, in the proper 
proportion to burn in the cylinder of the engine. Since this mixture must 
have definite proportions of fuel and air to burn completely, the carburetor 
must maintain the proper quantity at all times. Too large a proportion of 

gasoline will result in the escape of some un- 
burned carbon in the cylinder. Too large a 
proportion of air, on the other hand, will re- 
sult in some loss of power because the explo- 
sions will be weaker. The mixture of about 
15 parts of air to one of gasoline by weight, 
is correct for complete combustion, and should 
give maximum power. A somewhat leaner 
mixture will give better economy, but at the 
same time will give noticeable loss of power. 
Since it is impracticable to weigh the mixture 
of fuel and air, the operator adjusts the car- 
buretor according to the behavior of the en- 
gine. 

The accompanying sketch represents some of 
the parts of a very simple carburetor. The 
gasoline from the tank flows through the fuel 
line L, through a screen or strainer past the 
needle into the float chamber. When the gaso- 
C M c 




U\U»1U^I 



Carburetor — Lecture I Page 2 

line raises the float to a certain height in the float chamber, the float, by means 
of a suitable lever or arrangement of levers, closes the needle valve and pre- 
vents the entrance of more gasoline until some has been used. 

As the pistons travel downward in the cylinder on their suction strokes, the 
air which enters the bottom of the carburetor is drawn through the mixing 
chamber past the spray nozzle at a velocity so high that it sucks up a spray of 
gasoline from the tip of the spray nozzle. In the carburetor shown the mix- 
ing chamber is smaller than the main body of the carburetor so that air will 
pass through at a high velocity, even when the throttle is nearly closed and 
the engine is running slowly. The size of the opening in the tip of the nozzle 
can be adjusted by screwing the needle valve up or down to regulate the pro- 
portion of fuel to air. The throttle can be opened or closed to regulate the 
quantity of charge drawn into the cylinders. 

If an engine fitted with this carburetor is primed, started and warmed up, 
and the throttle is nearly closed in an effort to make the engine run slowly 
the quality of mixture, or the proportion of fuel to air can be adjusted by 
screwing the needle valve up or down. If the needle valve is screwed down 
too far the engine will miss and "pop back" and if it is set too lean will prob- 
ably die out entirely. This popping or back-firing takes place because a very 
lean mixture runs so slowly that there is no fire in the cylinder when the 
fresh charge comes in at the beginning of the next suction stroke. If the needle 
valve is opened more the engine will run smoothly when the proportion of fuel 
to air is somewhere near correct. When it is opened still wider the mixture 
becomes too rich and the engine runs at a slower speed; if it becomes still 
richer, the engine will misfire and race or lope with sooty, black smoke issuing 
from the exhaust pipe and if the priming cup is open the issuing flame will 
be yellow instead of blue or purple. 

If, after the needle valve has been adjusted to give the best quality of mix- 
ture, with the throttle nearly closed and the engine running slowly, the throttle 
is opened wide to make the engine run faster or pull a greater load, a larger 
volume of air will pass through the throat of the venturi tube or mixing cham- 
ber with very much higher velocity and the quality of the mixture will become 
entirely too rich. If, on the other hand, after the needle valve has been ad- 
justed to secure the bst possible qualities of mixture, when the engine is run- 
ning fast and the throttle is wide open, the throttle is closed to make the en- 
gine run slowly, the mixture becomes entirely too lean and the engine dies out. 



CMC 



Carburetor — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
CARBURETOR SECTION 

LECTURE II 

Vacuum Tank 

The gasoline tank on a motor truck may be located either under the driver's 
seat or at the dash, the gasoline flowing from it to the carburetor by gravity. 
In some cases, it is located beneath the rear axle beneath the frame or in some 
other position so low that either air pressure, or a vacuum tank is rquired to 
insure delivery of the fuel to the carburetor, particularly on an up grade or 
when the tank is nearly empty. Pressure is generally obtained by the use of 
the hand pump located on the dash. After it has been once established it may 
be maintained by a pump driven by the engine. The vacuum tank system is 
very popular with modern manufacturers. It provides an even flow of gaso- 
line at constant pressure to the carburetor. 

The principle of the vacuum system is not difficult to understand. The tank 
is divided into two chambers — upper and lower, the upper one being the com- 
partment in whch the gasoline from the tank is first received, the lower one 
is called the empty chamber and supplies direct to the carburetor. This lower 
chamber is exposed to the pressure of the outside air (atmospheric pressure) 
at all times by means of an open passage leading to the air vent. The upper 
chamber is connected to the gasoline tank by one pipe, and to the intake mani- 
fold by another. Two valves are operated by a mechanism connected to the 
float which operates in the upper chamber. One valve opens and closes the 
suction pipe to the intake manifold, and the other opens and closes the 
passage to the air vent. In the entire tank is empty, as happens when the tank 
has just been installed, the float will be at the bottom of the upper tank, and 
the suction pipe valve will be open and the air vent valve closed. In order to 
drain the gasoline to the upper chamber, it will be necessary to crank the 
motor over several times, with the throttle closed, so that nearly all the suction 
of the pistons will be exerted through the suction pipe, the upper chamber and 
the fuel pipe. Thus the gasoline will be sucked from the fuel tank to the upper 
chamber as it will be remembered that when the float is down, the suction 
valve is open, and the air valve closed. It is sometimes necessary to "prime" 
the upper chamber with gasoline through the small plug in the top to get the 
flow of gasoline started. As the gasoline flows into the upper chamber, the 
float rises, and when the proper level has been obtained a light spring on the 
float mechanism snaps the suction valve closed, and the air vent valve opens 
at the same operation. Thus, when the air valve is open the upper chamber is 
exposed to the open air, just like the lower chamber which is always exposed 
to it. In other words, both chambers are under atmospheric pressure. A pipe 
leads from the upper chamber to the lower, at the bottom of which is a flapper 
valve. When suction is exerted upon the chamber this valve is closed, but 
when both chambers are under the same atmospheric pressure, the weght of the 
gasoline in the upper chamber forces the valve open, and the gasoline flows 

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Carburetor — Lecture II Page 2 

into the lower chamber from where it is led through a pipe to the carburetor. 
As the gasoline runs out of the upper chamber, the float sinks, the air vent 
valve is closed and the suction valve opens, and the operation is repeated. 

This system provides an even supply of gasoline at a constant pressure to 
the carburetor, no matter how much gasoline is in the fuel tank, or whether 
the car is going up a steep hill or down, which are the main troubles of a 
plain gravity system. Neither are there any pump troubles, or flooding of the 
carburetor from too much pressure as in the pressure system. 

The usual source of trouble in the vacuum system is caused by a pin hole 
leak in the float, causing it to sink. It may be seen by the diagram that if the 
float does not rise, the gasoline will fill the upper chamber and be sucked right 
through the intake manifold into the suction pipe, without going to the car- 
buretor at all. This condition can usually be diagnosed by the evidence of 
black smoke and explosions from the muffler, and the choked action of the 
motor, which will hardly run at all. If the leak in the float can be found, it 
should be soldered, but if it cannot be located, a new float must be installed. 
These leaks are sometimes so small that it takes several days for the float to 
become filled and sink and therefore those microscopic holes are difficult to 
locate. They may often, however, be found as follows: The float which is. 
filled with gasoline by the leak is placed in a dish of very hot water (nearly 
boiling), so that the water covers the float entirely. The heat of the water 
vaporizes the gasoline in the float, and expands the vapor, which will escape 
through the leak and bubble up through the water. The exact spot must be 
marked. In order to get the gasoline out of the float, it is usually necessary to 
punch a little larger hole right where the leak is to be repaired, so that the 
gasoline can run out. Use very Ittle solder, as too much would increase the 
weight of the float, to an extent that it might not operate properly. 

Other troubles usually comprise the sticking of some part of the valve mech- 
anism, or the sticking of the flapper valve between the chambers. Those parts 
may be inspected by removing the cover of the tank. 

On almost every truck there is a suitable shut-off cock beneath each fuel 
tank and with it there is generally some form of trap to catch the water with 
a screen or strainer to hold back any dirt or foreign matter which might 
obstruct the gasoline line or the small passages in the carburetor. The driver 
should be familiar with the location of this shut-off in order that he may turn 
it off instantly in case of fire. It is advisable to open at least once a week 
the drain cock which is provided at the bottom of this trap to allow any water 
or sediment to escape. The arrangement of the tank is generally such that an 
emergency supply of fuel will be available by turning the shut-off cock to a dif- 
ferent position, or changing from a main to a reserve supply. The fuel line, 
usually a brass or copper tube, should be so screwed that it cannot vibrate and 
wear through or break loose at the fittings. 

When the speed of the engine increases, and the suction of the intake becomes 
greater, too much gasoline with relation to the amount of air is liable to be 
drawn into the mixing chamber. In view of this fact, various appliances and 
principles are used to compensate this tendency toward an overrich mixture at 
higher speed. In this connection the first that may be mentioned is "Air 
Valve Compensation." In this case, a secondary or auxiliary air valve under 
spring tension is opened more and more, as the speed and suction increase. 
The spring referred to is usually conical in shape, so that the large turns of 
the coil give a high tension while the smaller turns give greater tension, as the 
spring is compressed more. 

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Carburetor — Lecture II 



Page 3 



Air Vent 




From Gasoline Tank 



Upper Chamber 



Lower Chamber 




To Intake Manifold 



~~ *"" To Carburetor 
Sectional view showing interior construction of Vacuum Tank. 



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Carburetor — Lecture II Page 4 

With such a carburetor, after the engine is warmed and the throttle is set 
nearly closed, the needle valve can be adjusted to secure the correct quality of 
mixture for running slowly. The high speed adjustment is made by changing 
the tension of the adjusting spring so that the engine will respond properly 
when the throttle is opened without back firing and without pouring forth 
black smoke. The leanest adjustment which will allow satisfactory accelera- 
tion is to be preferred. On some carburetors the auxiliary air valve may be a 
single weighted valve or a series of valves held shut by gravity and opened 
by suction at high speed. 

Toward the improvement of the air valve form of carburetor much inventive 
genius has been directed. This is illustrated by the adoption of many con- 
trivances, mostly mechanical, each of which has some definite effect either de- 
sirable or otherwise. Among these may be mentioned: 

A. Interconnection of the air valve with the needle valve or metering pin 
which controls the main jet. 

B. Interconnection of the throttle with the needle valve or metering pin 
which controls the main fuel jet. 

C. Plain secondary jet to supply gas, in addition to that supplied by the 
main jet. 

D. Interconnection of the throttle with the mechanically controlled air 
valves. 

E. Interconnection of the air valve with the needle valve or metering pin 
to control the secondary jet. 

F. Interconnection of the spring controlled air valve with the dash pot 
which might be made to work in air or gasoline. 

G. A gasoline pumping device to enrich the mixture when the engine is to 
be accelerated. 

H. An accelerating well or small chamber containing gasoline which is 
sucked up suddenly when the engine speeds up. 

I. Weighted or loaded auxiliary air valve. 

J. The by-pass behind the throttle or under the edge of the throttle to in- 
sure the mixture for running idle or slowly. This may or may not be adjust- 
able. It is found on most modern carburetors. These will be discussed later. 

It is beyond the scope of this lecture to go into any extended explanation 
of the advantages and disadvantages of these numerous mechanical devices. 
It is sufficient to state that mechanical complication in the carburetor is un- 
necessary and in some cases undesirable. Foreign experience has taught us 
that carburetors free from mechanical complication and moving parts gener- 
ally give the best service under the conditions under which military trucks are 
operated. 

With an understanding of the operation of the elementary form of air valve 
carburetor, the driver or mechanic should be able, by studying the illustra- 
tions and directions in the manufacturer's instruction book, to make the nec- 
essary adjustments on a carburetor which is more complicated in construction. 

There is another way of compensating for the tendency of the mixture (from 
the mixing chamber with a simple spray nozzle), to become too rich at high 
speed and too thin at low speed. This is by regulating the flow of fuel instead 
of adding air by means of an air valve. There are two methods of accomplish- 
ing this result. These have worked out successfully on carburetors which are 
used extensively on motor trucks. One is to set the quality of the mixture 
approximately correct for high spjeed and wide open throttle conditions, and 

CMC 



Carburetor — Lecture II Page 5 

then add gasoline to it to keep the mixture from becoming thin at low speed; 
the other way is to set the mixture right at low speed and in some way so 
control the supply as to prevent the mixture from becoming too rich at high 
speed or wide open throttle. 

In the Stewart carburetor the size of the primary fuel orifice is increased 
as the auxiliary air is admitted. The primary air supply enters at "AA" and 
passes through drilled holes H, past spray nozzle located in mixing chamber 
at E. Gasoline from the float chamber comes through passages S, past needle 
valve of metering pin P, through spray nozzle at E, from which it mixes with 
the air to form a fine spray. Whenever the motor requires more mixture than 
can be supplied to passages H and mixing chamber E, the suction lifts the 
whole air valve A, which is a free fit in guide K, off of its seat at I, thereby 
admitting more air. As air valve A lifts away from tapered metering pin P, 
a larger quantity of gasoline is drawn up through the nozzle, thereby maintain- 
ing the desired quality of mixture. To the lower end of air valve A is attached 
a disc D, which is submerged in gasoline and acts as a dash pot to prevent flut- 
tering or too sudden opening of the air valve. To afford easy means of chang- 
ing the quality of mixture the height of needle P can be changed by a rack and 
pinion, MN, controlled from the driver's seat by suitable rod and lever mechan- 
ism. With this the driver can secure richer mixture for starting and can thin 
it out as the motor warms up. The taper of the pin and the weight of the 
valve are determined experimentally by the manufacturer and cannot be im- 
proved upon by one who is not an expert. 

The principle of compensation by use of compound nozzle and gravity fed 
well (Zenith Carburetor) is illustrated in figures 3, 4, 5 and 6. Figure 3 repre- 
sents a simple nozzle and mixing chamber, the mixture from which, as already 
explained, tends to become too rich at high and too thin at low speed. Figure 
4 represents two glasses of water arranged with straws; the harder one sucks 
on the straw on the left hand glass of soda water the more liquid he will get. 
No matter how hard one sucks on the straw on the right hand glass he cannot 
draw the liquid any faster than it is poured into the glass from the bottle. 
The harder he sucks the more air he gets with the liquid. 

Figure 5 represents the application of this principle to the carburetor con- 
struction. The liquid flows through the hole I into the well J. While the en- 
gine is running the suction draws the liquid out of the bottom of this well as 
fast as it runs in. The nozzle delivers a mixture of gasoline and air instead 
of a solid stream of gasoline. With the increase of air velocity there can be 
no increase in the quantity of fuel delivered up from the nozzle beyond the 
rate at which it flows into the well J. The quality of this mixture, therefore, 
becomes leaner and leaner as the quantity of air flowing through the mixing 
chamber increases. 

Figure 6 represents the combination of the two to form which is termed a 
compound nozzle. The tendency of one nozzle to supply a mixture which be- 
comes lean as the speed increases counteracts the tendency of the other to sup- 
ply a mixture which becomes rich as the speed increases. The result is prac- 
tically uniform mixture under all conditions of load and speed. 

When the engine stands idle the well J and the nozzle are filled with gaso- 
line almost to the height of the tip of the spring nozzle. When the engine is 
cranked this extra supply drawn from the well gives a slightly richer mixture 
at the start which is especially desirable. A more complete explanation of the 
actual construction of a carburetor of this type, with full instructions, can be 
found in the instruction book issued by the manufacturer of a car or of the 
carburetor. Carburetors of this type are extensively used in France and in 

CMC 



Carburetor — Lecture II 



Page 6 



STEWART CARBURETOR. 



r~<* 




OD 



CMC 



Carburetor — Lecture II 



Page 7 




CARBURETOR SECTION 



VSXS33- \ \ \ \ S S \J 

J*,,,,, j , , , , , , , ,-?y 

f 
E 



FIG. NO. 3. 





FIG. NO. 4. 




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FIG. NO. 6. 



Carburetor — Lecture II Page 8 

America both on motor trucks and on airplanes. Being free from moving parts 
they give a very little trouble and require practically no change of adjust- 
ment with moderate change of altitude or climatic conditions, a condition not 
true of a carburetor with air valve compensation. 

The new Stromberg carburetor — used on Liberty trucks — embodies several 
of the features of the Zenith, but does not use a compound nozzle. Instead, it 
has what is called an "Air-Bled Nozzle." The principle of the air-bled nozzle 
type will be drawn upon the blackboard. Gasoline flows through a hole which 
is controlled by a needle through the passage into the well. When the engine 
is started the air drawn through the larger venturi creates a very high suction 
at the smallest venturi. This suction draws gasoline through the small drilled 
holes at the throat of the venturi, through the vertical tube in the lower end 
of which is a small hole at the bottom of the well. 

As the suction becomes higher and higher, due to the large amount of gaso- 
line drawn, the depth of the gasoline in the well is lowered. As it is lowered 
a series of drilled holes are uncovered successively. More and more air is 
drawn through the "air-bleeder" and through the holes and mixes with the 
gasoline in the tube, thereby maintaining a correct proportion of fuel to air in 
the carburetor. The proper size of the bleeder and the sizes of the holes have 
been determined by the manufacturer and require no change. The quality of 
the mixture is regulated by the needle valve. 

In plain tube carburetors, equipped with the compound nozzle fitted with a 
gravity well (Zenith) plain tube carburetor fitted with air-bled nozzle (Strom- 
berg, Holley, etc.), the air velocity through the mixing chamber when the en- 
gine is running idle causes insufficient suction to lift the gasoline from the 
nozzle and produce a mixture. To allow smooth running idle and at low speed, 
a by-pass tube or feed behind the throttle is generally provided, and is arranged 
with an adjusting screw, by means of which the quality of the mixture pro- 
duced and fed in at, or just above the edge of the throttle can be regulated. 
This is called the low speed for idle adjustment needle. The majority of air 
valve carburetors are fitted with a similar tube. Generally, in this case the 
by-pass is not adjustable. 

The throttle arm on every cai'buretor is provided with an adjustable stop 
screw so that when the throttle control lever on the steering wheel is placed 
in closed position, the throttle will be held open just far enough to allow the 
motor to run idle at a slow rate of speed without danger of stopping. 

Many devices are used in connection with gasoline engines to make starting 
easier and to permit regulation of the quality of the mixture from the driving 
seat. A flooding device, known sometimes as a priming pin or tickler, is some- 
times arranged so that the float may be held down until the float chamber is 
full and gasoline runs out of the spray nozzle into the mixing chamber and the 
lower air passage. 

A priming or fuel pump is sometimes arranged so that the stroke of the 
plunger will inject a small stream of gasoline or spray of gasoline into the 
inlet manifold, or sometimes into the valve ports of the cylinder casting. 

A butterfly valve sometimes called a choker or strangler is sometimes pro- 
vided so that when it is closed it shuts off part or most of the air entering the 
carburetor. This insures higher suction and a richer mixture when the engine 
is cranked. This may be connected with the steering column or dash, so that 
the driver may use it to regulate the quality of the mixture when the engine 
is warming up as well as to make starting easier. 

CMC 



Carburetor — Lecture II Page 9 

A dash control may be provided for the needle valve or metering pin (or 
sometimes for the air valve spring) so that the driver may enrich the quality 
of mixture to make starting easier while the engine is warming up. 

On most engines the air is heated by being passed through a stove clamped 
to the exhaust pipe before it enters the carburetor. On some other engines, 
more heat is applied to the mixture at the carburetor or in the manifold after 
it leaves the carburetor. A few years ago it was a common practice to water- 
jacket the mixing chamber and the carburetor, and sometimes the intake mani- 
fold as well. In some modern designs the intake manifold is fitted into the 
inside of the cylinder block and being surrounded with hot water is kept com- 
paratively warm. On a great many modern engines that portion of the inlet 
manifold directly above the vertical type carburetor, where the mixture must 
take its first turn to go into the horizontal part of the manifold, is surrounded 
with a jacket fed with hot exhaust gases, from the engine. This "hot spot" 
gives very satisfactory results, except that some trouble is experienced due to 
clogging of the jacket and passages with carbon and oily soot. A few designers 
have cast the exhaust and inlet manifold in one piece. 

The disassembling of the carburetor, cleaning the parts and reassembling 
it and making adjustment is work which can be done to much better advantage 
by a mechanic or one thoroughly familiar with carburetor construction than by 
the driver. When an engine stops entirely, the driver should NOT take that 
as an indication that it is time to remove and disassemble the carburetor, but 
should first be sure that there is a supply of fuel in the float bowl and that 
there is fuel in the cylinders; he should next prime the engine and attempt 
to start it. If the engine runs for a few seconds and stops it is generally a 
fair indication that the ignition system is in order. If the engine will not start 
after it is primed, attention should be directed to the ignition system to deter- 
mine whether there is a good spark in each cylinder at the proper time. With 
or without the carburetor, the engine should start if the ignition system is in 
order, and the cylinders primed sparingly and are not warm and flooded with 
an excess of fuel. 

First ascertain that a good spark occurs at the spark plug. 

1. Engine will not start: 

(a) No gasoline. 

(b) Dirt in needle valve (prime pet cocks — race motor). 

(c) Supply pipe clogged or leaks, screen dirty. 

(d) Float stuck, leaving valve closed. 

(e) If engine is hot, and will not start, cylinders are full of too 
rich a mixture, open pet cocks, or remove spark plugs and 
crank several times with the throttle closed. Cut down on 
needle valve. 

2. Carburetor "floods": 

(a) Float sunk. 

(b) Dirt in float valve. 

(c) Float level too high. 

3. Engine backfires through carburetor: 

(a) Too lean a mixture. 

(b) Insufficient supply of gasoline, caused either by dirt in needle 
or float valve, or in feed pipe. 

4. Explosions in muffler — black smoke: 

(a) Too rich a mixture. 

(b) Float in carburetor or vacuum tank sunk. 

CMC 



Carburetor — Lecture II Page 10 

(c) Float valve held open by dirt. 

5. Engine misses at low speeds: 

(a) Carburetor adjusted either too rich or too lean. Too rich or 
too lean a mixture caused by one of the troubles enumerated 
above. 

(b) Poor gasoline. 

(c) Water in gasoline (drain float chamber). 

(d) Air leaks, around spark plugs, pet cocks, valve caps, cylinder 
head gaskets, or valves. 

(e) Choker in carburetor partly closed. 

6. Engine misses at high speeds: 

(a) Very rich or very lean mixture either by adjustment or by one 
of the causes enumerated above. 

Repair 

Carburetors may use either coi'k or metal floats. The cork floats sometimes 
become "water-logged" and sink. In this case remove the float and after 
allowing it to dry thoroughly, apply one or two smooth coats of shellac. 

A sunken metal float may be treated in the same manner as described in 
Stewart Vacuum System. If it is found necessary to adjust the float level 
either on account of flooding or insufficient supply of gasoline in the float 
chamber, the level may be changed either by adjusting nuts on the float valve 
or if no adjustment is provided, by bending the float arm. 

In case of flooding or an over-rich mixture, the trouble may arise from the 
float valve having a worn or grooved seat, so that it does not fit. The valve 
should be removed and ground carefully into its seat with a very fine grinding 
compound. 

Dirt or lime obstructing the spray nozzle or needle valve so that very little 
or no gasoline can get into the mixing chamber may be sometimes sucked 
through by priming the cylinders with gasoline, flooding the carburetor and 
cranking the engine with the throttle valve open. Allow the engine to race a 
little, and the obstruction will often be sucked through the nozzle. If the 
nozzle is adjustable, open the needle valve a couple of turns when the engine 
is started to make a larger opening. 

Another method is to blow compressed air through the carburetor, or if a 
drain plug is provided to remove same and poke a fine wire up through the 
spray nozzle. If this method fails the carburetor must be removed and taken 
apart to clean thoroughly. 

In summing up, propably the best advice that can be given regarding car- 
buretors is the old adage, "Don't monkey with the buzz-saw." Leave well 
enough alone. Drain the carburetor frequently to remove sediment, but do 
not attempt to improve upon a satisfactory adjustment, and make no changes 
in float level, or other major adjustments without first making sure that there 
are no other minor defects. Always consult the instruction book is one is 
available. 



CMC 



Carburetor — Lecture III Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
CARBURETOR SECTION 

LECTURE III 

Governors 

Governors are extensively used on trucks, tractors, marine and stationary 
engines. There are two reasons for using a governor, one being to regulate 
the vehicle speed, the other to regulate the engine speed. Where it is desir- 
able to limit only the vehicle speed of trucks, the transmission or front wheel 
type of installation is used. It is seat at whatever speed the car owner desires, 
is then sealed, and the driver can never exceed the speed for which the gov- 
ernor is set. 

The engine type of governor is used to prevent undue racing of engine at 
high speeds and staining the entire mechanism of the car, and incidentally 
wasting fuel and oil. As the transmission governor is seldom used on trucks 
and as it leaves the engine absolutely unrestricted at any speed except that 
in high gear, we will not go into detail about its construction. The engine 
type of governor regulates the number of revolutions of the engine and will 
keep it running at a definite safe speed, regardless of the load it is pulling, 
even if the throttle is wide open. The regular hand throttle lever or ac- 
celerator may be used for lower speeds. Should the clutch be sufficiently 
released when the engine is pulling a load or running on maximum speed, 
the engine positively cannot race. The engine governor also limits the vehicle 
speed because the engine cannot exceed the set speed. 

The construction of a centrifugal governor is as follows: On the water 
pump shaft is a carrier or arm supporting two bell crank levers, the outer 
end of the levers being directly connected to the butterfly valve of the car- 
buretor by means of a connecting link shaft, the inner ends having mounted 
thereon two metal balls. The action is as follows: As the speed of the shaft 
is increased, the balls by centrifugal force are thrown away from the shaft. 
In doing so the short arms are drawn toward the disc and draw the throttle 
arm or butterfly closed, shutting down the speed of the engine to the desired 
R.P.M. 

The governor formerly used on the Packard known as the hydraulic gov- 
ernor of the diaphragm type is located directly above the water pump. It 
is operated by the pressure of the water in the water circulating system and 
consists of a circular chamber divided by a flexible diaphragm of leather and 
rubber. On one side of the diaphragm is a water space through which passes 
the water of the circulating system. On the other side is an air space and 
the plunger head against which the diaphragm presses the plunger, is directly 
connected with the throttle valve. If a decrease in the load of the engine 
causes its speed to increase, the pressure of the water circulated by the pump 
increases and consequently the diaphragm exerts more pressure toward the 
rear tending to move the plunger and thereby close the throttle. Should the 

CMC 



Carburetor — Lecture III Paqe 2 

engine speed decrease the water pressure against the diaphragm is lessened 
and the throttle may open. 

There are several types of governors used, and while the general principle 
remains the same and the net results are maintaind, you will find during 
your shop exercise that the design and adjustment will vary considerably. 
The details will be treated in general in the following period. 



CMC 



Carburetor — Quiz Questions Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
CARBURETOR SECTION 

Quiz Questions 

1. Name the three methods of supplying the fuel from the tank to the 
carburetor. 

2. What method is generally used in heavy trucks? 

3. What devices are often found at the bottom of the fuel tank? 

4. Where is the fuel tank located? 

5. What attention should a trap or strainer receive? 

6. How often? 

7. If there is any indication of leakage in the fuel line, what precaution 
should be taken when the car is allowed to stand? 

8. State definitely what should be done when a truck or car takes fire? 

9. What can be used to make a temporary repair of a broken gasoline 
tank? 

10. What should be done with each end of this temporary repaired part 
to insure tightness? 

11. What materials can be placed on threaded gasoline connections or on 
gaskets to make them proof against gasoline leakage? 

12. What is the purpose of a carburetor? 

13. What is necessary to cause the fuel in the mixture to vaporize to any 
considerable extent? 

14. Is complete vaporization generally obtained or is the mixture wet? 

15. What would be the result of placing an inlet pipe closer to the ex- 
haust pipe? 

16. What would be the result of placing an inlet pipe entirely within the 
exhaust pipe and heating the mixture to an extremely high temperature be- 
fore it enters the cylinders? 

17. Explain the principles of the manifold used on the Liberty trucks. 

18. What are the indications of too rich a mixture? 

19. Of too lean a mixture? 

20. What is the purpose of a dash control? 

21. Is it better to run on a mixture slightly too rich or slightly too lean? 

22. If the mixture is as lean as it can be made without causing misfiring 
of the engine, will the engine develop full power? 

23. What effect does temperature have on the flow of fuel through the 
nozzle in the carburetor? 

24. On the vaporization of fuel in the manifold? 
CMC 



Carburetor — Quiz Questions Page 2 

25. Why does a cold motor fire regularly only when the throttle is nearly 
closed or when it is racing unloaded? 

26. Compare briefly the properties of gasoline with those of water and 
of molasses when cooled, warmed, and heated to a high temperature. 

27. What is meant by "loading"? 

28. What is done on a modern truck or car engine to reduce or prevent 
loading? 

29. Before any attempt is made to disturb carburetor adjustments, what 
other tests should be made? 

30. Before any adjustment on the carburetor is changed, what steps 
should be taken to insure that the trouble lies in the carburetor and not in 
the fuel line? 

31. Before any adjusting devices on a carburetor are disturbed, what step 
is it advisable to take in order that the old adjustment can be restored? 

32. What step should be taken when a carburetor begins to flood? 

33. If there is any question as to whether failure of the engine to start 
is due to the carburetor or ignition system, what step should be taken to 
insure supply of fuel in each cylinder? 

34. What will be the result of overpriming or of holding the choke valve 
entirely shut in an attempt to start an engine which is thoroughly warm? 

35. If the priming cup is opened, what should be the color of the issuing 
flame? 

36. Explain in detail what method should be pursued to insure easy start- 
ing of an engine in cold weather? 

37. What would be the advantage of priming with gasoline such as is 
used in the revolving cylinder type of airplane? 

38. How can carbide be used in priming? 

39. How can a motorcycle gas tank be used? 

40. Is it possible for a carburetor which has very little mechanical com- 
plication and which is free from multiplicity of moving parts and adjustments 
to give satisfactory quality of mixture under all conditions of service? 



CMC 



Motor Cycle — Lecture I Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
MOTOR CYCLE SECTION 

LECTURE I 
Engine 

No attempt is made herein to discuss the history or development of motor 
cycle motors. Consideration is taken only of the essential features of the 
type in universal service. This type is the two cylinder V. four cycle, sixty- 
one cubic inch direct air cooled gasoline motor. 

Upon all motorcycles supplied for Government service, regardless of manu- 
facture the above type is standard. There are two distinct types of cylinders 
in use in military motor cycles today. Both of these types, however, have the 
valves situated in a valve pocket. In one is the conventional "L" head design 
with the exhaust and intake valves side by side. In the other the intake valve 
is superimposed on the exhaust valve and operates in a valve cage inserted in 
the cylinder. The discussion of these two types is taken up later under the 
head of valve design. 

Upon the outer surfaces of the cylinder are found small fins or flanges. 
They are cast in such a manner that as thin a cross section of metal as pos- 
sible is maintained. Their purpose is to cool the cylinder by radiation. It 
is obvious that this motor is cooled efficiently only when the vehicle is in 
motion. This is the reason that particular stress is laid later upon one point. 
Never allow any driver to race his motor while the machine is not in motion 
and never leave the motor idling over half a minute at one time. In the top 
of the cylinder provision is always made for a plug or pet cock. This hole 
directly over the center of the piston, serves as a most excellent place to in- 
sert a scale when timing the motor. On the side of the cylinder is a small 
boss for the insertion of a priming cock. At the lower part of the cylinder a 
heavy flange is formed. Through this there are drilled four holes. Studs 
set in the crank case permit the cylinder to be securely fastened thereto. The 
inner surface of the cylinder, generally called the cylinder wall, is very accu- 
rately finished. After each cylinder has been bored it is inserted in an accu- 
rate grinding machine and this surface finished to the thousandth part of an 
inch. This high finish is easily marred; hence the great care that must be 
taken to be sure that the motor is being properly lubricated. 

The piston of the military motor cycle is made of cast iron. It is conven- 
tional in design. Three grooves are provided for piston rings, all of which 
are above the piston pin. The surface of the piston is also very accurately 
ground and finished. Bosses are provided, through which are drilled the holes 
for the piston pin. 

In motorcycle practice the pin proper is a press fit into the piston, being 
held in place by a special cotter key. The surface of the piston pin is ground 
so that it presents a suitable surface for the bushing provided in the upper 
end of the connecting rod. 

The connecting rods are of I beam cross section. The bronze bushing for 
the piston pin is pressed into the upper end of the rod. The lower end of the 
CMC 



Motor Cycle — Lecture I Page 2 

rod or crank pin bearing for many years baffled the best engineers to find 
a bearing that would give satisfactory results. The treatment of this par- 
ticular part of the motor is an extremely interesting engineering attainment. 
One of the rods is forked. A boss is provided on the lower side to prevent 
any tendency of spreading. The other rod fits into the forked member. Both 
are independent, in no way interconnected. Hai-dened steel bushings are 
pressed into these lower ends. The crank pin itself is of high grade steel, 
hardened and ground to size. 

Four rows of rollers in suitable retainers provide the necessary bearing. 
If this bearing at any time develops any play, it is possible to take this up by 
inserting sets of oversize rollers which the manufacturers make up. Any 
handy man can perfoi'm the operation, since it does not require such expert 
knowledge as is in the case in scraping and fitting a bronze or Babbitt bearing. 

The crank pin, in addition to providing a bearing surface for the lower 
connecting rod bushing also acts as a distance piece between two flywheels. 
It is tapered on both ends. This tapered surface is accurately ground and 
registers with similar tapered holes in each flywheel. A special nut and lock- 
ing device obviates any possibility of this part working loose from vibration. 

There are two flywheels in this type of motorcycle motor. They are entirely 
contained within the crank case. These wheels are usually cast; and necessary 
counter weights are provided for in this process. At the center of each 
wheel is provided a tapered and accurately finished hole. The main shaft and 
sprocket shaft have tapered ends which fit their respective wheels. In ad- 
dition to this taper fit all shafts, crank pins, main and sprocket shafts are 
keyed in place in the flywheel. 

The main shaft registers in the flywheel at one end. It provides a bearing 
surface for one of the crank case bushings and upon its outer end is keyed 
and fastened the small pinion gear which operates the timing gears and the 
valve mechanism of the motor. 

The sprocket shaft registers in its flywheel and forms the bearing surface 
for the other crank case bushing. At its outer end on a ground taper with 
key is fastened the engine drive sprocket. 

The crank case bearings for the main shafts are usually of bronze. The 
bearing of the sprocket shaft is annular, ball, or roller. 

The crank case is usually of cast aluminum or cast iron. It is divided 
longitudinally into halves. When the halves are bolted together, they form 
an oil tight reservoir. The flywheels revolving in the case splash the oil upon 
the other working parts. Upon its outer surface are formed the holes or 
lugs which permit the motor to be bolted into the frame. The upper surface 
of the case is accurately machined and eight studs are inserted. The cylinders 
are fastened to the crank case by means of these studs and in such a position 
that their center lines form an angle of 45 degrees. When extended both of 
these center lines will pass through the center line of the main and sprocket 
shafts. A chamber is cast upon one side of the crank case, in which provision 
is made for housing the cam and valve operating mechanism. 

The studs or shafts upon which the various timing gears operate are se- 
curely fastened into 'this case. The stud upon which the cam revolves some- 
times called the cam shaft, is situated in the middle of the case and directly 
above the main shaft pinion gear. 

The intake and exhaust cams are formed integral with the secondary 
pinion which operates them. This set of cams actuates the valves of both 
cylinders. The secondary gear or pinion, which is an integral part of this 

CMC 



Motor Cycle — Lecture I Page 3 

cam, meshes with the main shaft pinion. Upon all military motorcycles the 
cam gear is marked so that when removed from the motor it can be replaced 
again in its proper position relative to the main shaft pinion. 

In the upper part of the timing gear case are found bushings provided for 
the valve lifter pins. The motion imparted by the cam is transmitted to the 
lifter pins through a series of small levers, called lifter levers or roller arms. 
In one design these lifter levers have sliding contact with the cam face. In 
another design the ends of these arms are fitted with hardened steel rollers, 
which give a rolling contact between the roller arm and the cam face. The 
purpose of these lifter arms is to multiply the effect of the cam action. Con- 
siderable space and weight are saved by employing this type of design. 

The valve-operating push rods are small hardened steel pins. On the upper 
end of each pin a screw adjustment is provided. A certain amount of clear- 
ance must be allowed between the end of the valve stem and this push rod; 
hence the adjustment. 

Two distinctly different valve designs are used in military motorcycle en- 
gines. In one of these the conventional L head design is used with the intake 
and exhaust valves side by side in the cylinder pocket. To remove them from 
the cylinder a hole is provided in the top of the pocket. Special plugs are 
screwed into these holes. In the intake valve plug a hole is drilled and tapped 
to provide for the insertion of the spark plug. The valve springs are of con- 
ventional design. They are retained in tension by the valve spring collar. 
This collar is usually held in place by a small key passing through a hole 
milled near the end of the exhaust valve stem. Both valves are of the same 
size in this design. They are of the mushroom type and are provided with 
45 degree seats. The stem and push rod mechanism is protected from pre- 
mature wear from road grit erosion by means of the valve spring covers. 
These are telescopic in design. When screwed into place they cover the ex- 
posed part of the valve mechanism entirely. 

In the second type of valve design the intake valve is mounted in a cage 
and is super-imposed on the exhaust valve. The exhaust valve is conven- 
tional and corresponds with the description of the previous design. Instead 
of having a plug inserted over the exhaust valve, however, the cylinder is 
machined out to permit the insertion of the intake valve cage. This cage sits 
in the cylinder in such a manner that no gaskets are required. The shoulder 
of the cage is ground into the seat so as to form a gas tight joint. A small 
housing which covers the intake valve stem and spring is inserted over the 
cage and the entire assembly locked in place in the cylinder by a special lock 
nut. A large hole is provided in the side of the cage, which registers with 
the intake manifold. This makes a passage for the gaseous mixture into the 
cylinder when the valve opens. The intake valve used in this cage is of the 
mushroom type. The valve head is equal in size to that of the exhaust valve, 
but the stem is much shorter. The valve being lighter, does not require 
such a heavy spring to operate it. Hence the spring is smaller. The spring 
is retained in tension by means of spring collar and key. 

The intake valve spring housing previously mentioned acts as a bracket to 
hold the intake valve operating rocker arm. This is a small lever that trans- 
mits the action of the intake valve cam to the end of the valve stem. Be- 
tween this rocker and the end of the intake valve lifter pin in the timing gear 
case is a long rod called the intake valve push rod. This rod is also provided 
with a screw adjustment which makes it possible to adjust the clearance be- 
tween the rocker arm and the valve stem. 

CMC 



Motor Cycle — Lecture I Page 4 

In addition to housing the valve operating mechanism the timing gear case 
contains other parts that perform important functions. 

As explained previously the flywheels of the motorcycle engine are con- 
tained within the crank case. They are of such size that they displace most 
of the air contained in it. The pistons are connected to the same crank pin ; 
in their reciprocating motion both descend to the bottom of the stroke at 
approximately the same time. This makes for a great variation in the amount 
of air contained in the case when the pistons are at the two extremities of the 
stroke. At a high number of revolutions per minute quite a heavy crank case 
pressure results. For efficient operation and lubrication this pressure must 
be relieved. In the military motorcycle this relief is accomplished by a rotary 
valve. This valve opens from the crank case into the timing gear case. It is 
of the rotary type and is formed integral with the pinion which operates it. 
In one make of motorcycle of military use this pinion is driven from the main 
shaft pinion. In another make it is found to be driven by the cam gear. The 
method of driving and placing the valve is entirely a matter of designing 
convenience. The operation of this valve, of course, is synchronized with 
piston action. The pinion is marked so that when removed from the motor 
it may readily be replaced in its proper position. This pressure is relieved 
from the timing gear case by means of a pipe at the top of the crank case. 
This pipe conducts the superfluous oily vapor away from the case, across the 
top of the crank case between the two cylinders, then downward to a point 
under the machine. In this way the oil is discharged on the road, leaving 
the engine base clean. In some motorcycles this oily vapor is used to lubri- 
cate the engine chain. 

Another mechanism found interconnected with the timing gear is the me- 
chanical oil pump. This instrument draws lubricating oil from the supply 
tank and forces it into the crank case. An adjustment is provided which en- 
ables the driver to regulate the amount of oil so delivered. An oil pipe leads 
from the supply tank to one of the valves of the pump. A piston operated 
by a small pinion interconnected with one of the timing gear train actuates 
the piston. Oil is drawn through this valve on the downward stroke of the 
piston and is then forced through another valve into the crank case of the 
motor by the upward stroke of the piston. The adjustment provides a means 
of regulating the stroke of the piston and in addition the amount of oil 
drawn from the supply tank and forced into the motor on any one stroke. 

At the end of the crank case is pi'ovided a bracket for the ignition device 
or magneto. This instrument is so mounted that its tapered drive shaft ex- 
tends into the timing gear case. After it has been bolted in place on the 
crank case a pinion, which is the last gear in the timing gear train is keyed 
and bolted upon this taper. In order for the spark to occur at the proper 
place in the cycle the movement of the magneto armature must also be prop- 
erly synchronized. This subject is discussed in detail later on, but is men- 
tioned hei'e merely to show that the pinion gear must maintain its proper po- 
sition in relation to other gears in the train. The magneto is also discussed 
in detail in another chapter. 

The compression release mechanism is also housed within the timing gear 
case. This is a system of levers that enables the driver to raise the exhaust 
valves on the compression stroke of the motor, thus replacing the compression 
and making it easier to start the motor. The mechanism is usually inter- 
connected with the spark advance control on the handle bar. 

A cover is provided for the timing gear case, which is readily removable 
for the inspection and adjustment of the parts contained therein. Never 

CMC 



Motor Cycle — Lecture I Page 5 



allow this cover to be removed for any reason whatsoever by any except an 
experienced motorcycle mechanic. If this warning is disregarded, serious 
trouble is bound to result. 

At the top of and midway between the cylinders is situated the carburetor. 
It is bolted to the manifold flange. The carburetor, its construction and ad- 
justment are taken up separately later. 

The manifold is inserted into the cylinders in special nipples. A special 
locking device of gland nut and tapered packing bushings makes an air tight 
joint at this point. Great care must be taken in fitting these parts, as air 
leaks in the manifold system result in an unevenly running motor. 



CMC 



Motor Cycle — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
MOTOR CYCLE SECTION 

LECTURE II 

Clutch and Transmission 

In Lecture No. 1, we discussed the general construction of the motorcycle. 
In the shop period following the lecture you had occasion to come in contact 
with the clutch. 

The duties of a clutch as you know are principally to permit the engine 
to run while the motorcycle is stationary and also to enable one to change 
gears, and when released, while in motion, to coast. 

Harley-Davidson Clutch 

This clutch is of the dry plate type. The only attention it requires is 
proper adjustment. It runs on two rows of roller bearings. Between them 
is a small channel containing an absorbent material. An oil hole is provided 
on the outside of the clutch, through which lubrication oil may be squirted 
into this absorbent ring. This retains the oil upon the surface of the roller 
journal. Oil inserted here once a week is sufficient. 

If it is noticed that the clutch is slipping and does not hold properly when 
pulling hard through sand or mud, or when climbing hills, it should be ad- 
justed. Before turning the clutch adjusting screws make sure that the adjust- 
ment of the clutch lever is correct as explained in the next paragraph. 

If the clutch lever has no free motion when in the extreme forward posi- 
tion, the clutch may slip; and it is always necessary to see that this adjust- 
ment is correct before tightening the adjusting screws. The clutch does not 
hold even though the adjusting screws are tightened, if the adjustment of the 
clutch lever is not correct. On the other hand the clutch does not release 
properly if the hand lever has too much play. 

To be sure that the clutch holds and releases properly, the lever must have 
Yz to % inch free motion at the top when in the extreme forward position. 
If the clutch slips and it is seen that the adjustment of the clutch lever is 
correct, it is generally possible to tighten the clutch sufficiently by giving 
each of the six adjusting screws one half turn to the right. These screws can 
be reached through a small hole in the chain guard, without removing the 
latter. Care should be taken to see that the six s"crews are given the same 
number of turns, regardless of how hard some of them may turn. As men- 
tioned one half turn each is generally sufficient, but if it does not tighten the 
clutch enough, a second half turn, making one full turn for each screw, should 
prove to be enough. These adjusting screws are self-locking; therefore, be 
sure that each screw drops into its seat properly after each half turn. 

If the clutch lever has no free motion when in the forward position, loosen 
the nuts on the clutch and pull the rod until this free motion is obtained. 

CMC 



Motor Cycle — Lecture II Page 2 

One quarter turn makes a big difference. These nuts are reached through 
the large hole in the middle of the chain guard without removing the guard. 

A special double ended socket wrench is provided in the tool kit for making 
this adjustment. It is necessary to loosen the small lock nut before turning 
the large adjusting nut. After turning the adjusting nut be sure to reset the 
lock nut firmly. 

Sometimes it may be found that the clutch engages too quickly, or that 
there is too much free motion when the clutch lever is all the way forward, 
in which case the clutch does not release. This can be remedied by tightening 
the adjusting nuts. 

Indian Clutch 

The Indian clutch is also of the dry disc type. When disengaged it also 
runs on a roller bearing. There are 22 hardened steel rollers in this bearing. 

If the clutch does not hold when engaged and if it permits the motor to 
race, loosen the lock nut "C" (sketch 5) and unscrew "A" half a turn. 
Tighten "C" and test the clutch. If it still slips, screw "A" out another turn. 
Two or three adjustments may be necessary to get the clutch so that it holds 
properly. Do not withdraw screw "A" more than half a turn at a time. 
This screw is acted on by the clutch release worm shaft; and as the driving 
discs wear thinner, the ends of this shaft and screw "A" eventually come in 
permanent contact and prevent the discs engaging tightly. Backing off the 
screw "A" compensates for the wear on the discs and allows them to engage 
fully as when new. 

If the adjustment of screw "A" does not remedy the slipping of the clutch, 
the four adjusting screws "B" should be tightened to increase the contact 
pressure between the discs of the clutch. 

Loosen the screws "I" and move locking ring "2" as far as it will go. This 
releases the screw "B" for adjustment. Tighten each screw one turn and 
try the clutch under load for pull. If it still slips, give each another half 
turn. Two or three adjustments may be necessary to get the clutch to hold 
properly. Replace the locking ring and tighten screws "I" after the clutch 
is finally adjusted. Turn the adjusting screws evenly, never one more than 
the other. 

When the machine is idle, always leave the clutch engaged. This relieves 
the tension of the springs and increases their life. If the drive is harsh or 
jerky, push the hand lever slightly until a smooth drive is obtained with 
slipping. Do not put any oil on the clutch discs. 

Brakes 

Frequent inspection of brakes should be required. Detailed instructions 
for the adjustment of both types are given herewith. 

Harley -Davidson. — If the foot brake does not hold, remove the pin "E" 
connecting the clevis of the brake rod to the brake arm. Loosen the clevis 
lock nut "F" and screw the clevis "G" farther on the brake rod until the de- 
sired adjustment is made. Caution : Do not set the brake too tight. With 
the machine on the stand and the brake released the wheel must turn as 
freely as before the brake was adjusted. 

If the hand brake does not hold, as is the case at times owing to natural 
wear, and when the position of the rear wheel has been changed to adjust 
the chain, the proper adjustment can in most cases be obtained by merely ad- 

CMC 



Motor Cycle — Lecture II 



Page 3 



O 



O 



o 








INDIAN CLUTCH 
SKETCH NO. 5. 



CMC 



Motor Cycle — Lecture II Page 4 

justing the band eye bolt "A" and the clamp "D." Before the making of any 
adjustment it is advisable to remove the long drive chain and to set the ma- 
chine on the stand. If the brake does not hold properly loosen nut "C" a 
few turns. Then tighten nut "B." Be careful that the brake is not set tight 
enough to drag; and to prevent this, turn the wheel after making this adjust- 
ment. The wheel must be perfectly free after the adjustment has been made 
and the brake lever must bear against the stop when released. If the lever 
does not bear against this stop, brake action is lost. In this case readjusting 
of the frame is necessary. 

Indian Brakes. — The external brake is operated by a finger latch on the left 
handle bar and can be applied by pulling up on this lever. The internal brake 
is operated by the pedal on the right footboard. To adjust the external brake 
proceed as follows: (See Sketch 7). Remove the cotter pin that retains pin 
"A" and take out "A." Next lift up screw "B" from the clevis where it is 
connected with "A" and turn it to the right two turns, screwing it into "C." 
Now replace "B" and "A" as before and test the brake by running the motor 
on the stand. If it does not hold satisfactorily, screw "B" into "C" another 
turn or two. When the brake is released, it should not drag on drum "D." 
To test for dragging, spin the rear wheel by hand with gear shaft lever in 
the neutral notch and the clutch engaged. If the rear wheel does not spin 
freely, see if the external brake band is dragging. If such is the case, loosen 
the screws on frame clamp "E" and move the clamp backward toward the rear 
end of the frame just a little. Test the brake for dragging and continue 
moving the clamp very gradually until the wheel runs free with the brake 
released. Then tighten clamp "B" and replace the cotter pin in pin "A." 
When the brake is on hard there should be a clearance of at least 1 % inches 
between the finger latch and the handle bar grip. If the latch lever comes too 
close to the grip, the maximum pressure cannot be obtained. The proper 
clearance for the finger lever may be obtained by moving clamp "E" forward 
or backward after the brake has been adjusted. 

To adjust the internal brake proceed as follows: Remove cotter pin (1), 
(Sketch 5), loosen nut (2) by turning to the right, loosen lock nut (3), and 
turn screw (4) to the right three or four turns. Now test the brake with the 
motor running on the stand. When the brake is on hard, the foot pedal should 
be at least \ x k inches from the foot board. After the proper brake adjust- 
ment is obtained, tighten nuts (2) and (3) and replace cotter pin (1). If 
the foot pedal comes too close to the foot board or touches it, full braking 
cannot be obtained. Neither should the pedal come too high when released. 
Proper position can be obtained by loosening lock nuts (5) and (6) on either 
end of the long brake rod (7) and by turning this rod. Turning it to the 
right haises the foot pedal; turning to the left lowers the foot pedal. Be 
sure that the lock nuts are retightened after adjusting brake rod. 

Hub Construction 

Front Huh. — The central member of the front wheel containing the front 
wheel bearings and providing on its outside extremities a means for attaching 
the spokes of the wheel. 

Rear Hub. — The central member of the rear wheel containing the rear 
wheel bearings and provides on its outside extremities a means for attaching 
the spokes, brake mechanism and rear driving sprockets. 

The front and rear hubs should be packed with grease every 3000 miles. 
Under no circumstances should the use of any graphite grease be allowed on 
the ball bearings. To disregard this causes wear of the bearings. 

CMC 






Motor Cycle — Lecture II 



Page 5 




KAKLEY DAVIDSON 
SKETCH NO. 6. 




INDIAN BRAKE 
SKETCH NO. 7. 



*=»«jP =■*£= Q3> 



CMC 



Motor Cycle — Lecture II Page 6 

All hubs should be entirely disassembled, cleaned and repaired every 
3000 miles. 

Lubrication 

Since proper lubrication is the most important single consideration in 
connection with motor cycle practice, it is necessary to know something of 
lubricants. Upon the selection of the proper lubricant for a certain duty 
depends the efficiency of the mechanism. 

For clutches, gear case, and other gearing the lubricant may range from 
heavy oils to the semi-fluids. Graphite in the flake form is a very fine lubri- 
cant. If it is mixed with a small quantity of oil to increase its fluidity, it 
may be used with good results in any part of the mechanism except the engine. 

The oil which escapes past the piston rings into the combustion space is 
subjected to the high temperature generated therein by the combustion of the 
fuel. If its heat-resisting qualities are poor, it burns. Its combustion being 
incomplete, as a rule, a quantity of carbon tends to accumulate on the piston 
head and in the combustion chamber reducing the efficiency of the engine. 
Too much oil applied to the cylinder wall, or poorly fitting rings, cylinder 
scored or out of round, are indicated by excessive oil consumption. From 
750 to 800 miles per gallon of oil may be considered of good average, although 
some makes of machines in the hands of experienced operators exceed this 
figure. 

Oils and greases must be renewed at intervals, as the lubricant deteriorates 
with the entrance of foreign matter. The addition of gasoline or other fuel 
oils tends to lower its viscosity as well as its flash point and to reduce its 
efficiency. Sand, dust and particles of metal gradually find their way into the 
lubricant, rendering it worthless. 

It should be made an iron bound regulation that the motor should be 
cleaned internally every five hundred miles. This cleaning is accomplished by 
flushing the motor with kerosene. It helps to loosen up and remove the car- 
bon which may be accumulated in the combustion chamber, to keep the piston 
rings in good condition, and also to clean thoroughly all of the old oil out of 
the crank case. This practice is recommended even though the best grade of oil 
is used. It proves a quick and inexpensive way of keeping the motor in good 
trim. The details of this flushing process as well as the removing of carbon 
deposit from the pistons and cylinders are taken up under a separate head. 

Over-oiling is also to be carefully guarded against. Its symptoms are baf- 
fling to any but an experienced motorcycle mechanic. If the crank case of the 
motor becomes so hot that the hand cannot be placed on it after the motor has 
been run for some time, the motor is almost invariably full of oil. Generally 
an oil-filled motor does not show any smoke at the exhaust. For that reason 
do not try to determine the amount of oil in the crank case by watching for 
smoke at the exhaust. 

A motor that is oil-filled is bound to heat up; in fact the oil will reach the 
boiling point, greatly retarding the pistons and their downward stroke. Loss 
of power and speed is a natural result. 

Over-oiling is a more prevalent cause of unsatisfactory motor service than 
is generally supposed. It becomes so bad in some cases that the enamel upon 
the crank case of the motor becomes discolored. The condition may be 
avoided by careful attention to the periodic flushing of the motor and to the 
adjustment of the mechanical oiling device. 

Lubrication systems are classed as gravity, splash, semi-splash, pressure 
and positive feed. All are used to some extent, but in motorcycle practice 

CMC 



Motor Cycle — Lecture II Page 7 

the splash, semi-splash and positive feed systems practically cover the field. 
In any system the object is to have the lubricant reach the designated point 
at the time and in the quantity required. 

In all motorcycles in military use the lubricating oil is drawn from the 
main supply tank and forced into the motor by a special mechanically oper- 
ated oil pump. After reaching the bottom of the crank case it is spread to 
all other parts of the motor by the splash from the flywheels. 

The care and adjustment of this oil pump are taken up under a separate 
heading. 

Oil cups are distributed at various other parts of the machine besides the 
motor proper. Oil should be placed in these daily. 

The grease cups on the front fork rocker arms should be filled with a 
good quality of non-fluid oil at least once a week. They should be screwed 
down a little each day. 

The front hub and rear hub should be packed with grease every 3000 miles. 
Under no circumstances should the use of any graphite grease be allowed on 
the ball bearings. To disregard this causes wear of the bearings. 

For transmission the manufacturer's advice should be followed. Some 
motorcycles require that heavy oil be used in this case. In other types the 
oil used for motor lubrication is suitable. 

The clutch bearing also requires periodic attention. A hole is provided in 
the side of the clutch housing, and oil should be inserted here every 500 miles. 

In spring frame motorcycles the spring leaves and various joints should 
receive periodical attention. 

The chains are also in need of cleaning and lubrication if good service is to 
be expected of them. Both chains should be removed every 500 miles and 
thoroughly washed in a pan of gasoline. 

It is possible to purchase a special chain lubricant. This is in a grease 
form. Some of it should be melted in a tin vessel and the chain dipped in it 
while it is in the molten state. This compound is usually made up of graphite 
and tallow. After the chains are removed the superfluous grease may be re- 
moved from their outer surfaces and the grease may then be applied again 
to the motorcycle. 

The construction of a motorcycle chain is such that it requires internal 
lubrication. Any lubricant such as oil applied to its outer surface serves only 
as a substance to hold grit and very rapidly wears both chains and sprockets. 

Motorcycles more than any other type of road vehicle require efficient 
lubrication. 

The right kind of lubricant properly and periodically employed is an abso- 
lute insurance against ninety per cent of the troubles you have to contend 
with. To slight the recommended practice results in the equipment being 
rapidly worn out. 



CMC 



Motor Cycle — Lecture HI Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
MOTOR CYCLE SECTION 

LECTURE III 

Road Troubles 

In this lecture road troubles are outlined and their remedy explained. All 
faulty valves, spark plugs, brushes and breaker points are separately dealt 
with and methods of repair prescribed, starting with valves. 

Valves do not seat: poor lifter pin or push rod adjustment: One of these 
members may be broken and be the cause of a valve being held open. Raise 
the valve spring covers and by means of a thickness gauge be sure that there 
is between .006 and .008 inch clearance between the tappet and the end of the 
valve stem when the motor is cold. If there is less than this it causes trouble 
on account of the expansion of the valve stem as the motor heats. If greater 
than this, it tends to destroy the correctness of the timing and to decrease the 
valve opening. The over-head intake valve adjustment should be made with a 
cold motor, allowing about .004 inch between the end of the valve stem and the 
rocker arm. Care should be taken that the cam is in such a position that the 
valve is fully closed before making any adjustments. 

Valve Stem Bent. Seat Warped: Care must be used in removing valve 
springs not to bend the valve stems. If they are bent, they should be replaced 
by new ones. If the seat is warped, the valve should not be reground (see next 
paragraph). Always grind in a new valve to its seat. 

Seat Pitted: If the valves are pitted and cause a loss of compression they 
must be reground. The motor should be taken from the frame and the cylin- 
ders removed for this operation. Before the grinding in of a valve the seat 
should be faced with a reamer. Pitting of the valve seat is caused by a poorly 
fitted valve and seat surface. A pitted seat should not be reground with a 
valve grinding compound for the following reasons: 

(1) Excessive grinding is necessary to remove the pits in the cylinder and 
from the seat. 

(2) The valve being considerably harder than the cylinder seat becomes 
lower after much grinding. This allows the valve to seat deeper in the wall 
chamber. As a result the clearance between the valve and the cylinder when 
the valve is in the raised position is reduced. Also the motor is not properly 
scavenged and loads up with burnt gases. By the use of a reamer, a minimum 
of stock is removed. 

(3) Excessive grinding or lapping ruins the straight face of the valve and 
cylinder seat and allows only a very narrow seat. 

Valve Key Sheared Off: If the valve cover is raised, this trouble may be 
ascertained by inspection. Remove the spark plug and insert a tool to hold the 
valve to its seat. Raise the spring and collar into place and insert a new valve 
spring collar key. 

CMC 



Motor Cycle — Lecture III Page 2 

Valve or Cylinder Seat Cracked: Replacement. 

Valve Spring Broken : Raise the valve sleeve and the valve and remove the 
old spring. Replace it with a new spring. 

Lift Mechanism Sticks: Raising the valve cover shows whether the valve 
is operating. Sometimes the valve sticks in the guide owing to gummy oil. 
Cleaning with gasoline may serve to remove the trouble. 

Valves do not Lift: There may be four causes for this: 

(a) Roller or Lifter Arm Broken: Remove the timing gear case cover 
and examine the members. If broken, replace them with new ones. It will be 
necessary to remove the cam also; but it must be replaced according to 
instructions. 

(b) Lifter Pins and Pushrods Loose: Sometimes the lock nut on the lifter 
pin adjustment may work loose and allow the adjustment to recede so far that 
the valve is not opened. 

(c) Pinion Gear Key Sheared: The motor has to be entirely retimed if 
this condition obtains. 

(d) Timing Gears Stripped: They must be replaced and the motor 
retimed. 

Valves Timed Wrong : This may be due to the fact that : 

(a) Gears were removed. 

(b) No key was in the pinion. 

(c) New gears were incorrectly fitted. 

If any of the above conditions obtain, a complete retiming of the motor will 
be necessary. This, of course, refers to the time of opening and closing the 
valves. These points are designated in two ways; either by degrees or by the 
piston position measured in inches. The word "cycle" means a series of events 
in regular order or sequence. 

Spark Plug. 

Defective Spark Plug: If the spark plug is defective, it may be caused by: 

(a) Cracked Core: Replace core. 

(b) Points Set Improperly: The space between the spark plug points 
should be .022 inch. A gauge is provided for making this adjust- 
ment. 

(c) Electrodes Oxidized: Clean the points with emery cloth and test. 
If the plug still fails, replace it with a new one. 

(d) Plug Oil Soaked: Take the plug apart, wrap a small strip of sand- 
paper or emery cloth around the core, and revolve the core several 
times with the fingers. Be sure to make the electrode tight so that 
it will not leak compression. 

(e) Sooty Plug: Clean with gasoline and emery cloth. 
Brushes, 

Brushes Oil Soaked : Remove the spring or screws, as the case may be, and 
remove the brush holder. Care must be taken not to damage the rubber gasket. 
Clean the brush and holder with gasoline and remove all oil from the collector 
spool. 

Collector Spool Oil Soaked: Remove the brush holders, dip a piece of cloth 
in gasoline, wrap it around a lead pencil, and insert it in the brush hole. Ro- 
tate the magneto by turning the motor over slowly and carefully a few times 
to insure thorough cleaning. Be very careful not to injure the collector spool 

CMC 



Motor Cycle — Lecture 111 Page 3 



as it is very delicate. Grease and dirt may be removed by forcing a gunful of 
gasoline through the spool housing opening. Blow out the gasoline with a tire 
pump before restarting. 

Brush Holder Cracked: Examine these closely for small cracks through 
which the electric current may escape. Sometimes these cracks are hard to 
find. If the brush holder is of hard rubber, cracks may be detected by smelling 
the rubber after running the motor on the one good cylinder. Defective 
holders must be replaced by new ones. 

Brushes Worn: The carbon brushes must be free to move and project one- 
quarter inch from the end of the brush holder. If found to be worn, they 
must be replaced. 

Breaker Points. 

Circuit Breaker Points out of Adjustment: The proper distance between the 
platinum contact points when fully separated should be .020 inch. A gauge 
of the proper thickness is provided upon the special magneto wrench for meas- 
uring this adjustment. If the distance is more or less than this, correct the 
adjustments; then try to start the motor. Be sure the adjustment is correct 
for both cylinders. 

Circuit Breaker Points Pitted. The platinum contacts should be kept clean 
and properly adjusted. Should the points become pitted, they may be smoothed 
by the use of a very fine jeweler's file in order to permit them to come into 
perfect contact. Be sure the filed surfaces are parallel, and readjust them 
after filing. 

Circuit Breaker Points Worn. If the plantinum points are so badly worn 
that filing does not correct the defect, they must be replaced by new points. 



CMC 



Motor Cycle — Lecture IV Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
MOTOR CYCLE SECTION 

LECTURE IV 

Parts and Repairs 

A. Spare Parts. 

a. Conservation. 

All spare parts such as cylinders, pistons, piston rings, wrist pins, etc., 
must be kept in a coating of oil or grease to prevent rusting. Paint-finished 
parts such as gasoline tanks, oil tanks, frames, wheel rims, sidecar bodies, 
chainguards, etc., must be kept packed in paper and straw to prevent damage 
to the finished parts. All breakable parts such as spai'k plugs, lens, etc., 
should be handled in a neat and orderly way so as not to cause misplacing of 
parts which would be liable to cause serious damage to the more delicate parts. 

b. Ordering from catalogue. 

A. When ordering from catalogue care must be taken that the proper 
name, order number, serial number, code name and number (if sent by tele- 
graph) and the exact number of parts to be ordered be given. If unable to 
find a catalogue or if one is not handy one should be able to sketch the part 
needed and send it to the spare part depot. 

c. Methods of Stocking. 

M.T.C. supplies and property in store will consist of all serviceable property 
not in use and not covered by memorandum receipt, and all unserviceable prop- 
erty. Whatever is the character of these supplies they will be orderly and con- 
veniently arranged in the storehouse or other place of storage, designated for 
their care and protection. So far as possible the serviceable supplies should 
be left in the original packages in which they are received. Supplies which 
have been removed from the original packages, herein designated as loose 
supplies, will be carefully and properly arranged in the order of the property 
account as far as practicable, in bins, shelves, or other suitable places provided 
for the purpose. 

Where the loose supplies are in excess of requirements to meet current issues, 
the excess quantities should be properly packed in suitable boxes, cases, etc., 
under the direct supervision of the quartermaster or his assistant, who should 
verify the account. These packages are to be sealed and their contents certi- 
fied to by the quartermaster. They may then be classed original packages, the 
contents duly indicated on the outside of the box or crate. 

With a view of knowing at all times the quantity, kind and size of supplies 
on hand in original packages, a detailed record of each package and its con- 
tents will be kept in a suitable blank book. 

All serviceable articles of the same description should be arranged together, 
a separate location being reserved for all unserviceable ones. To facilitate 
issues, inspections, and stock taking, packages containing articles of the same 

CMC 



Motor Cycle — Lecture IV Page 2 

description should be arranged together. Each tier of a pile should have the 
same number of packages if practicable and each package which has not been 
opened on receipt should be so arranged that the markings, showing contents, 
are exposed to view. 

To insure a free use of fire apparatus and to facilitate the removal of pack- 
ages, the upper tier of each pile should be far enough from the ceiling to per- 
mit the up-ending of the top package, high enough to lower the package out to 
the aisle. The height of piles is further governed by the minimum safe load 
which the floor will sustain. Special precaution must be taken in this regard 
when it becomes necessary to store supplies in buildings which are not con- 
structed for such use. 

The two warehouse systems which are in general use for arranging pack- 
ages in a store room are the block and the numerical systems. 

(a) In the block system the packages are arranged in solid blocks three 
or more packages deep; each package of a block contains the same kind, and 
the same number of articles; lateral aisles are used between blocks only; 
and the markings of all boxes in the same pile face in the same direction, so 
that as successive boxes are removed the markings showing contents come 
into view. It is used where large quantities of supplies are stored and deep 
piles are not inconvenient. 

(b) In the numerical system the packages are arranged in piles not 
more than two packages deep, with lateral aisles between every second row, 
and with markings showing contents of each package exposed to view. It is 
the more generally used system when the quantity of supplies to be handled 
is relatively small, as at mobilization or concentration camps or for ordinary 
use where the forces to be supplied do not exceed one division. It facili- 
tates issues and shipments. A combination of both systems may be used to 
advantage on any occasion. 

It is often impractical with very small packages to have the markings ex- 
posed, but with packages of standard size (each 32x19x15) it may be accom- 
plished by placing them end to end, two deep, perpendicular to, and with the 
marking toward the lateral aisles. The depth of each of such piles thus ar- 
ranged and likewise the distance between consecutive lateral aisles is 6 ft. 6 in. 
and the requisite floor space of the lateral aisles for ordinary trucks is approxi- 
mately one half that occupied by the total floor space, after that required for 
the main aisles, fire passages, and a clearing space has been deducted. 

When issues are frequent, shelving is convenient for storing small articles, 
and it may be improved by hinging one side of each of the necessary number 
of empty packing boxes and stacking them with the open side outward. This 
is practically the same as the bin system which is commonly used in storing 
the smaller items. With this system it is advantageous to use a standard size 
bin such as 24 1 / 2 xl8 1 /2xl8". The bins may have removable and interchange- 
able rule dimensions, adaptable to the special shape and quantity of goods to 
be stored. 

B. Definitions. 

Stowing is the putting away of things, usually stores, in their proper places 
according to proper method. 

Items. — Any one kind of stores to be put in one place. Difference in size, 
shape, nature, quality, weight, color, make, brand, or style will generally deter- 
mine different items. 

Lot. — A quantity received and stowed at any one time, e. g., 50 cases, 24 in 
case. 

CMC 



Motor Cycle — Lecture IV Page 3 

Unit. — A quantity easily handled or normally issued at one time, e. g., 
Wholesale, 1 case, 24 in a case. 

Article. — Any single piece, e. g., 1 can. 

C. General Instructions for Handling of Stores. 

Group Piling. — Stores are piled single or in multiples of five. Goods may be 
piled singly up to ten in a column. Beyond this the columns are made as high 
as the space will permit but of whole groups of five only. Groups are not 
broken to fill in a remaining space too small for a whole group. Thus every 
column or article small enough to be piled in groups of five will contain some 
multiple of five and will be uniform for that article. For instance, if a bin 
holds 24 packages of letter heads piled snug on top, the column will be made 
of 20 packages only, viz., 4 groups of 5 each. 

Accessibility. — Goods will be placed so as to be as easily accessible as pos- 
sible, those more frequently used being in the handier locations. 

Minimum Handling. — Consistent with the above, they will be placed so as 
to require as little handling as possible in receiving, stowing and removing. 
Other things being equal, heavy bulky goods will have the shortest haul. 

Uniformity. — The piles and rows of any item will be of uniform quantity 
for ease in counting. 

Concentration of Stores. — In stowing a bulky item of stores in quantity, 
effort will be made to concentrate it. Thus two platforms opposite each other 
(cross side aisles) will be filled in preference to two adjacent platforms. Any 
excess over two platforms full will then be stowed in the aisle between. The 
effort will be to find two empty platforms opposite, which will be filled, and the 
excess stowed in aisle between. 

Side Aisles. — Side aisles may be used for stowing when the sections on 
either side are full of the same material. 

Main Aisles. — Main aisle space adjoining a wall may be filled to parallel full 
rows and aisles of the same material on either side. Platforms will be placed 
for goods stowed in aisles. 

Removals. — Removals will be made first from aisle spaces. No goods will be 
removed from a regular row until adjoining aisle space has been entirely 
cleared. 

Stoiving Area. — In any area to be filled, stowing is commenced at the back 
left-hand corner, and brought forward, each row of goods being completed to 
the front before a new row is started. Piling is done as soon as the nature of 
the goods permits and as high as possible, so long as the piles are stable, the 
uniform groups are presei'ved, and the pile does not come within 16 inches of 
the sprinkler pipes. 

Stowing Volume. — In any cubic space to be filled, stowing is commenced at 
the back left-hand corner, and carried on vertically until one column is com- 
pleted. This is made the first of a row of such columns brought to the front 
and completed. The second row of columns will commence as did the first, in 
the farthest left-hand corner of the remaining available space, and be built up 
in the same manner. 

Several Items. — If there is room in any single storage space for more than 
one item, the second is stowed similarly to the first, but beginning at least one 
inch to the right of the area required for the first item. Additional items will 
be stowed in the same way. 

Maximum. — The maximum quantity ordinarily stowed will occupy not more 
than 75% of the space available. The remaining space is reserved for times 
of special need. 

CMC 



Motor- Cycle — Lecture IV Page 4 

Reversing.— Goods will be placed all one way, unless for stability in piling it 
is necessary to reverse part of a column. Such will be reversed singly or in 
groups of five, according as they are regularly piled singly or in groups. The 
same dimensions, however, will lie the same way. 

Uniformity of Placement. — All articles of one kind will be placed uniformly. 
Preferably the width of the article is made to lie the longer way of the storage 
space. If, however, space is economized to a marked degree (at least 25%) by 
placing the articles some other way, it may be done. 

Labels. — Labels, or other means of identifications, will be placed all one way, 
showing outward, if consistent with other rules. 

Lots. — Different lots of the same items of stores will be kept distinct and 
separated by a space of at least one inch if in bins, or three inches if on plat- 
form. Each lot has its own separate tag and lot number. 

Columns and Rows. — Each full column of goods will have the same number 
of articles as each other, and each full row will have the same number of col- 
umns as each other. Only the last row and column may remain incomplete, 
containing odd quantities. 

Wrappings. — Articles with defective wrappings will be placed last, in order 
that they may be removed first. The person stowing the goods is responsible 
for seeing that the tying or wrapping on packages is in as good condition as 
his facilities enable him to secure. This includes the putting on of new 
wrapping when necessary ana feasible. 

Removing. — In removing goods from storage in any one lot the last goods 
to be put in place are removed first, and further removals are made in just 
the reverse order to that in which they are placed. This means the cleaning 
up of incomplete columns of stores before complete ones are touched. In the 
case of more than one lot of any one item the lots are drawn from in order 
of age commencing with the oldest, unless specified on the issue. Not until all 
the goods of one lot are removed from any part of a storage space and the tag 
removed is that part available for stowing a new lot. 

Aisles Must be Kept Clear. — The real reason for taking pains that stowing 
of stores shall be orderly and systematic is to be able to get at what is wanted 
when it is wanted, with the least possible expenditure of time and effort. This 
involves having what you want on hand in sufficient quantities and knowing 
where it is. The only way of getting at what is wanted is by means of the 
aisles and passage-ways provided for the purpose. It is axiomatic, therefore, 
that the aisles should be of only such width as is required for the necessary 
passing and handling of the goods to be stored. It is equally fundamental 
that they cannot be obstructed by things left standing in them or by the pro- 
jection of things stored along their margins. The delay caused by unexpect- 
edly encountering a blocked aisle is always wasteful — likewise, the danger of 
damage to goods projecting from the proper bounds of either storage spaces 
or conveyors is obvious. 

Widths. — Aisles should be planned according to their use and the size of con- 
veyors or materials to be handled in them. Main aisles for two-way passing 
of trucks may need to be six or eight feet, or even more in width, according to 
conditions. Side, connection-aisles, or those straight through the building, for 
one-way passing, need be only comfortably wider than the trucks to pass 
through. Blind side aisles, ending in a wall, or for trucking, normally should 
be wide enough to allow the truck to safely turn around. This is especially 
true where four wheel or elevation platform trucks are to be used. Thirty 
inches is the standard width for aisles between bins or shelves where the con- 
tents are package goods carried by hand. 

CMC 



Motor Cycle — Lecture IV Page 5 

Identification. — The clear and complete identification of each item is equally 
obvious. The same item must not be called by different names at different 
times; furthermore, the name of each item must be so distinctive that it can- 
not be confused with any other. This leads, in many cases, to the careful 
classification and symbolization of all items in stores according to systems to 
be mentioned later. The symbol, being short, direct, and standing for only one 
thing, is a convenient tool for the accurate identification of stores. 

Issuable Units. — Goods should be stowed as nearly as possible in the units 
in which they will be issued, eventhough this requires the breaking of the 
units in which they are received. This is based on the fact that the time ele- 
ment required for unpacking is less important when the goods are first received 
than when they are called for issue. As a precaution against unnecessary 
loss from depreciation, it is obvious that the stock should be kept moving in the 
sense of always using the old lots first. 

Methods, Standards. — The importance of establishing in writing some de- 
fined methods of placing and removing the various classes of items need not be 
emphasized. The very effort to determine the methods forces attention and 
decision, for the time being at least, on the one best way under the circum- 
stances. More than that, it is true that the consistent following of even a poor 
standard brings better results than the haphazard and uncertain following of 
the best standards. The more completely a poor rule is followed, the more 
clearly will its failings be revealed and the better can it be revised. 

Neatness. — Standard methods for piling each class of goods will insure neat- 
ness and uniformity. Then the exceptions to good piling, by their very con- 
spicuousness will be their own signal for correction. "Publicity is a potent 
factor in keeping things right." Therefore, unnecessary covers, doors, and 
other protections, behind which wrong practice may be concealed, should be 
avoided. Besides leading to precision in handling and making carelessness 
more noticeable, such uniformity greatly facilitates the accuracy and speed of 
inspection and count. So far as possible, stores should indicate their own 
count. Hence the importance of uniformly regular rows, layers and columns. 
This is the chief reason for preferring columnar to pyramidal piling. The 
quantity in a single pyramid may be calculated by mathematical formula, but 
difficulties arise as soon as part of the pyramid is removed. "How much is. 
left" is an all-important question and it should not be necessary to count each 
article to find out. Columnar piling in rows and sections, with only one last 
section, row, column, or package containing an odd quantity, is the simple 
solution of this problem. For the same reason, the use of easily calculated 
decimal units for the quantities in sections, rows, columns and sometimes pack- 
ages is desirable. The instruction specifying that piling may be done in single 
units up to 10, and after that only in multiples of 5, illustrates the point. 

Double Space. — The allotment to each regularly carried item of twice the 
space needed for each regular lot of the items received is, where sufficient 
space is available, well worth while. It insures accuracy and simplicity in 
handling the different lots, each being kept separate and the old lot always 
being used first. It also results in less frequent need of locating parts of the 
same item in different places. Where only the single space required for a lot 
is reserved for it, and a new lot comes before the old lot is used up, it is often 
necessary to put part, if not all of the new lot somewhere else, there being no 
room for it in the space with the old lot. This process, repeated often enough, 
leads to a constant shifting of the location of given items and results in con- 
fusion. In some cases where the storekeeper is responsible for the quantities 
on hand, he loses sight of some parts of an item and calls for more before he 

CMC 



Motor Cycle — Lecture IV Page 6 

really needs them. This means unnecessary investment and the added liability 
to loss from spoilage. Some plants have found that the cost of the double 
space system suggested above was well repaid by protection against such loss. 
The less intelligent and skilled the help, the greater is the usefulness of the 
double space system. It is more nearly "fool-proof." 

d. Repairing of Discarded Parts. 

The repairing of discarded parts is an important item in the conservation 
of spare parts. The re-boring of cylinders that are out of true is a great 
saving both of cost and of material. The welding or brazing on of cooling pins 
is a successful operation, and is a great factor in the reclaiming of discarded 
cylinders. Discarded pistons that are worn may be used over with the help of 
over-size piston rings. Broken crank cases may be reclaimed if welded by an 
expert only, as the halves of the crank case must be true to each other, that is, 
the main bearings must be exactly in line with each other. Dented oil, gas and 
exhaust pipes may be repaired by use of a plug, which is the exact size of the 
inside diameter of the pipe. Worn wrist pins or piston pins are hardly ever 
used again but may be softened a little and used as a punch. Worn roller 
bearings may be machined over and refitted to different bearings. Broken 
porcelains in spark plugs is very common and may be repaired by inserting 
new porcelains. Bolts and nuts that have worn or stripped threads may be 
drilled over with a tap drill and retapped. Worn valves may be refaced in an 
engine lathe. Intake and exhaust levers may be rebushed or, if they are soft, 
they may be tempered over. Worn piston rings are not used again because it 
does not pay to machine them over. Ignition wires that are discarded because 
of their terminals being broken may be rejoined by refacing them in a lathe 
and grinding them in their respective place. Damaged mufflers are easily 
reground by a mechanic. Broken chains may be used as repair links and car- 
ried as extra links in tool box. Clutch discs can be relined easily with clutch 
lining. Brakes are also easily relined with lining. Broken frames can be 
brazed and repaired by use of a welding outfit. Broken spring leaves are used 
in many different ways for different repair jobs, they are very valuable to the 
motor mechanic. Bent up mud-guards, tanks, etc., can be reclaimed and re- 
paired by the average tinsmith or mechanic. Discarded tires and tubes may 
be used again as blowout patches. Broken ball-bearing units can be saved 
and the ball bearings used over if they measure up by the use of a micrometer. 

e. Estimating Damage and Time of Repair. 

The estimating of damage done to a machine on the road and if the ma- 
chine was in the repair shop are two entirely different items. In estimating 
the damage done on the road the rider should give all possible data on the 
•external damage and as near as possible, the internal damage, done to the 
machine. The damage can be estimated by observation and by testing or 
turning over the damaged parts. When the machine is in the repair shop the 
estimated damage can be checked up and the ability of the operator as an 
estimator of damage done on the road can be determined. In regard to time 
necessary for repairs, the rider must have a clear understanding of the 
facilities which the repair shop has in regard to that cei'tain job. 



CMC 



Motor Cycle — Quiz Questions Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION TRAINING BRANCH 

Company Mechanics' Course 
MOTOR CYCLE SECTION 

Quiz Questions 

1. What are the main differences between the Indian and Harley-David- 
son motors? 

2. Describe in detail how you would retime a motor. 

3. The cam shaft makes 1250 complete revolutions. How fast is the 
motor running? 

4. Describe the action of the intake valve on the Harley-Davidson motor. 

5. Describe every stroke of the motorcycle motor. 

6. How is the flow of gasoline into the carburetor regulated? 

7. Name the indications, defects, and remedy of a rich mixture. 

8. Describe the construction and use of the butterfly valve. 

9. What type of clutch is used on the motoi-cycle? 

10. How much oil is used in the clutch? 

11. What type of transmission is used on motorcycles? 

12. How many sets of gears are meshed with the low gear in? 

13. What is the use of the "Secondary Shaft?" 

14. What is meant by "seat mast tube?" 

15. How do you adjust chains? 

16. How is the motor suspended in the frame? 

17. Describe the mechanical oil pump. 

18. What care should be given the oiling system? 

19. What kinds of brakes are used on motorcycles? 

20. What is the cause and remedy of a squeaking brake? 

21. Can a sticking valve cause a miss? 

22. If motor stops dead, what is probably the trouble? 

23. What are the indications of pre-ignition? 

24. What are the causes of compression loss? 

25. What is meant by tread casing and bead? 

26. How do you prevent tube and shoe sticking together? 

27. Is it safe to use the compression release to stop the motor? Why? 

28. Which is the most important to give care : tires, lubrication, car- 
buretor, or spark plugs? 

29. Describe a piston ring, and its use. 

30. Explain the starting system. 

31. What is meant by "out of time?" 

32. What is meant by "half time gear?" Give example. 

CMC 



Motor Cycle — Quiz Questions Page 2 

33. What is the engine speed in revolution per minute, if the piston in 
No. 1 cylinder makes 2800 strokes per minute? 

34. How would you adjust exhaust valves on the Indian. 

35. Tell the position of both valves on each stroke of the motor. 

36. How is the amount of fluid gasoline in the carburetor determined? 

37. How is air admitted into the mixing chamber? 

38. Describe the following: Venturi tube; jet; needle valve; tell their use. 

39. What is meant by "burnt out clutch?" 

40. Describe the clutch operating mechanism. 

41. What is the principle of a transmission? 

42. Describe the "direct drive." 

43. Describe the "spline shaft." 

44. What type of rear axle is used in motorcycles? 

45. What adjustments are necessary after tightening rear chain? 

46. How is a broken spring in front fork (H.D.) removed? 

47. Explain fully the entire oiling system. 

48. How is a motor harmed by lack of oil? 
48. How do you adjust the hand brakes? 

50. Do you ever use oil on brakes? If so, what kind? 

51. How do you detect a "missing cylinder?" 

52. What are the causes of a spitting motor? 

53. If no spark is delivered at the plug head, where is the trouble? 

54. What are the causes of a sluggish motor? 

55. Describe the steps of a tire change. 

56. What is the correct pressure for a motorcycle tire? 

57. What is the most important item of motorcycle optration? 

58. How do you stop the motor? 

59. Would not more power be secured by using less air? Why? 

60. Is a rotary valve ever used on a motorcycle? If so, where? 

61. Describe fully the different types of valves in use in military motor- 
cycles. 

62. What is pre-ignition and its causes? 

63. How many revolutions does the engine make when the intake valve 
of number one cylinder opens 1550 times? 

64. Name every part necessary to operate a valve. 

65. Explain how the burning of gas and air can be made to turn the rear 
wheel of a motorcycle. 

66. Describe fully the float and float valve system and uses. 

67. How many air intakes in a carburetor and the use of each? 

68. Where are the spray nozzle and needle valve located and what is the 
operation of each? 

69. What is the clutch and why is it necessary? 

70. What care does the clutch require? 

71. What is a gear-lock, spline shaft and counter-shaft? 

72. How is the power transmitted with the machine in second gear? 

CMC 



Motor Cycle — Quiz Questions Page 3 

73. What is meant by "progressive" type transmission? 

74. Where is the "head" of the frame and the "cradle?" 

75. How would you tighten the chain from the engine to the clutch? 

76. Describe the front fork rocker arms. 

77. Describe the mechanical and splash oiling systems in the motorcycle. 

78. What are the results of: (a) Too much oil; (b) Too little oil? 

79. Where and how does the hand-brake operate? 

80. How often do you inspect your brake system? 

81. How would you detect a valve miss? 

82. What do you mean by a short circuit? 

83. What does a light blue smoke indicate? A black smoke? The remedy 
for both? 

84. What causes poor compression? 

85. How would you repair a nail puncture? 

86. What attention would you give small cuts in the casing? 

87. What is the use of the muffler? 

88. What device is used in stopping the motor? 

89. What is the most important thing to do before starting the motor? 

90. What attention do the hub bearings require? How? How often? 



CMC 



Administration — Lecture I Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ADMINISTRATION 

LECTURE I 

Accountability and Responsibility of Sergeant Mechanics and Others 

M.T.C. Personnel 

Systems of Cataloguing Spare Parts 

Accountability and Responsibility 

i 
The following is quoted from Par. 657 Army Regulations on the subject 
of accountability and responsibility for public property: 

"Accountability and responsibility devolve upon any person to whom 
property is intrusted and who is required to make returns therefor. Re- 
sponsibility without accountability devolves upon one to whom such prop- 
erty is intrusted, but who is not required to make returns therefor. An 
accountable officer is relieved from responsibility for property for which 
he holds a proper memorandum receipt. A responsible officer is not re- 
lieved from responsibility for public property for which he has given 
memorandum receipt until he has returned the property to the accountable 
officer or has secured memorandum receipt from a successor, or until he 
has otherwise been relieved by the operation of regulations or orders." 
It is essential in dealing with property to determine the difference between 
the terms "Accountability" and "Responsibility" as used in connection with 
government supplies. 

Accountability for property devolves upon any officer who is required to 
keep records of, and render returns for, the property with which he is charged. 
Such property may or not be in his possession, but his accountability is con- 
cerned only with the matter of accounting for the property, not with its actual 
possession. Only commissioned officers may be accountable for property ex- 
cept in extreme cases of ungarrisoned posts when Ordnance and Quartermas- 
ter Sergeants may act as accountable officers. 

Responsibility with or without accountability, devolves upon any one to whom 
public property is intrusted and who is answerable for its care and use. Re- 
sponsibility is practically inseparable from possession. Both officers and en- 
listed men may be responsible for property held by them. Whether or not the 
officer is also accountable depends not on the element of possession but on 
the question of whether or not he is required to account for or render returns 
for the property under consideration. 

The term "Accountability" as used herein implies that certain periodical 
reports or returns of property transactions are required, and vouchers to 
evidence such transactions, both as to receipts and transfers, are necessary 
to support entries on such reports or returns. 

CMC 



Administration — Lecture I Page 2 

The term "Responsibility" as used herein, implies a military and pecuniary 
obligation on the part of an officer or other person to control and preserve 
material entrusted to his care in such manner as to serve the best interests 
of the Army. There will be a great many officers and other persons who will 
not be required to render accounts for motor vehicles intrusted to them, but 
the fact that such officer or other person is not required to render an account 
or return of said property in no sense relieves him of the responsibility, as 
above defined, which is automatically imposed upon him when any property 
of the Army comes under his care or control, nor of the obligation to main- 
tain according to conditions of the service, a reasonable record or statement 
of his stewardship, or to furnish evidence, when properly called for, of the 
disposition which he has made of motor vehicles for which he is responsible. 

Responsibility and Accounting for M.T.C. Vehicles. — At M.T.C. reception 
parks at base ports, where motor vehicles are initially received by the Ameri- 
can E.F., and at such M.T.C. reception or other parks as may be designated to 
receive vehicles purchased in Europe, officers or other persons who are author- 
ized to receive said vehicles will, upon delivery to them, promptly acknowledge 
receipt of the same by the accomplishment of bills of lading, ships manifest, 
or such special forms of acknowledgment or receipt as may be required by 
the several staff corps or services, transportation systems, factories, etc., or 
agents of the same. Officers or other persons receiving said vehicles will be 
held responsible for their proper care and preservation, forwarding to desig- 
nation, and for the prompt rendition of such reports and registration data, 
as are required by special regulations promulgated by the Director Motor 
Transport Corps, and for such accounting for said vehicles as is hereinafter 
prescribed. 

Duties and Responsibilities. — (a) Company Commander: He is responsible 
for the efficient operation, maintenance, and discipline of his company. He 
must constantly bear in mind that the value of his organization is measured 
by the efficiency with which it operates, and by its ability to cope with 
emergencies. 

(b) Second Lieutenant. — This officer is the direct assistant of the com- 
pany commander, and has such duties and responsibilities as are given him 
by the company commander. 

(c) First Sergeant. — He is the truckmaster and the executive of the 
company, He sees that all orders, regulations, and other requirements are 
properly carried out; that the men perform their duties properly; and reports 
to the company commander any cases of neglect or violation of orders re- 
quiring disciplinary action. He should be a man chosen more for his adminis- 
trative and executive ability and his efficiency in handling men than for his 
mechanical knowledge. The mechanic may well be chosen for his ability 
as a mechanic, irrespective of his ability to handle men, but the first sergeant 
should be a man of force, as his prime duty is to maintain discipline for the 
efficient operation of the company. 

(d) Mechanic and Assistant Mechanics. — The mechanic and assistants are 
under the direct control of the first sergeant. The mechanic should be held 
responsible that the necessary repairs are made to the mechanical equipment 
of the company. He is in charge of the repair truck, and tools and equip- 
ment pertaining thereto. He should sign for the tool equipment and issue 
it to the assistant mechanics on proper receipts. He should be held responsible 
that this equipment is properly maintained and that any shortages by dam- 
age, loss, etc., are properly made up. Normally, he should see that the assist- 

C M c 



Administration — Lecture I ■ Page 3 

ant mechanics are properly qualified, and should instruct them in their work. 
In order to perform their duties properly, the mechanic and assistant me- 
chanics should be thoroughly familiar with the instruction books issued by 
the maker of the vehicles furnished to the company. 

(e) Company Clerk. — He has charge of all records, reports and corre- 
spondence of the company. As he is habitually called upon to notify mem- 
bers of the company as to orders and instructions received, or to call upon 
them for the rendering of prescribed reports, and in consideration of other 
incidents where he must exercise authority, he has the rank of sergeant. 
Other duties for him are prescribed by the company commander according 
to local conditions. 

(f ) Property Sergeant. — He is responsible for all supplies and equipment 
not actually issued to individuals, and will keep the necessary records there- 
for. He is responsible, moreover, that all issues of property are properly 
receipted for by the persons responsible. He keeps the property under his 
charge clean and in proper order, and should have a list up to date of all 
property and its disposition. All dealings with the quartermaster or supply 
officer not requiring the personal intervention of the company commander, 
should be carried on by him. 

(g) Mess Sergeant. — He has direct charge of the mess hall, kitchen, and 
all matters pertaining thereto, including supervision of the cooks or other 
men working in the kitchen. He draws the rations, sees that they are eco- 
nomically used, makes up bills of fare, sees that the kitchen, mess hall and 
premises are clean and sanitary, and that all orders in reference thereto are 
properly carried out. His authority to contract debts, or expend money 
should be carefully watched and checked by the company commander per- 
sonally. In some cases, the duties of mess sergeant are performed by the 
property sergeant, but this depends on the special aptitude of the man, as 
well as on other local conditions in the company. 

(h) Chiefs of Sections. — Each chief of section (assistant truckmaster), 
is responsible for the discipline, instruction and all other matters pertaining 
to the personnel of his section ; for the operation, repair and upkeep of the 
equipment assigned thereto. He is the intermediary between the men of his 
section and the truckmaster or company commander. His supervision ex- 
tends to all the details connected with his section, including police and sani- 
tation of quarters, seeing that his men are provided with the necessary equip- 
ment and clothing. All orders for his section either to the various members 
of his personnel or to the units of his equipment, should be given to him. He 
should assure himself that his section is in proper condition at all times by 
making regular and systematic inspection of his men and equipment. He 
should examine all his vehicles on their return from work, and see that the 
drivers have taken proper care of them and that the proper repairs are made. 
In his absence, for any cause, a suitable man should be designated to per- 
form his duties. 

(i) Driver. — He keeps his vehicle and its equipment clean and in proper 
repair and working order. Inorder to do this, he utilizes his spare time while 
not on duty to do the minor work required thereon. He should be especially 
inquired to attend to the proper lubrication of all parts and truck mechanism, 
and to report promptly any defect noted or repair needed. In transporting 
material or supplies, he will see that the vehicle is not overloaded, that the 
cargo is properly loaded and lashed, and ordinarily he is responsible for its 
safe delivery. He should be familiar with the mechanism of his vehicle and 

CMC 



Administration — Lecture I Page 4 

its proper operation, and for this purpose he should be thoroughly familiar 
with the contents of the instruction book issued by the makers of the vehicle. 
He should be required to wear proper uniform when driving. 

Cataloguing Spare Parts 

The supplies necessary for the operation and maintenance of motor ve- 
hicles are of two classes: (a) materials and spare parts common to all motor 
vehicles, irrespective of type or make, and (b) spare parts pertaining to each 
type, make or model of motor vehicle. The supply section of each overhaul 
or service park will have a proper stock of the first class, and in addition 
will have the necessary stocks of articles of the second class for the repair of 
the make and type of vehicles pertaining thereto. 

All articles necessary to the operation and maintenance of motor vehicles 
have been catalogued. Catalogue No. 1 contains the materials common to 
all motor vehicles. The parts special to each type or make of vehicles are 
listed in special catalogues. In each catalogue articles are designated as 
"expendable" or "non-expendable." This notation has no bearing on the 
subject of property accountability, which is regulated by orders issued from 
General Headquarters, A.E.F. The designation of "non-expendable" indi- 
cates that an article so marked will only be replaced or issued when the 
broken or unserviceable article accompanies the requisition or request there- 
for. If it is impossible to return the broken article, a certificate covering the 
reasons therefor must accompany the requisition. There are several purposes 
for this requirement. It insures the return of the broken part for any salvage 
work that may be necessary to reclaim it. It prevents a transport unit from 
keeping a large junk pile that will interfere with its mobility or entail the 
loss of much material that is capable of salvage. It allows a technical ex- 
amination of worn out or broken, faulty material, or faulty design. This 
last information is essential to the proper operation of the Maintenance 
Division. 



CMC 



Administration — Lecture II Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ADMINISTRATION 

LECTURE II 

Requisitions 

How to Use Parts Catalogue in Preparing Requisition 

In requisitioning spare parts from time to time, it is necessary in order that 
there be no mistake about the exact part required, that it be described exactly. 
There are a great many parts of a motor vehicle which are almost alike, are 
called by the same name, but which are a trifle different in make or dimensions. 
To describe a part accurately, therefore, might involve almost writing a letter 
about it and even then, frequently, the description might be inaccurate. For 
this reason catalogues have been prepared showing the parts of standard 
motor vehicles and assigning to each part an individual number. 

In ordering such parts, therefore, all that need appear on the requisition is 
the part number, the name of the catalogue used, and the amount required. 
No further description of the' part is necessary, for the number, when the 
catalogue is consulted, is amply sufficient. 

The first pages of the catalogue are devoted to drawings of the various main 
sections of the engine, with lines drawn pointing out each part and its number. 
In this way, any mechanic or driver, even if he is unfamiliar with the tech- 
nical name of a part needed, can locate it on the picture and requisition for it. 

The middle part of the catalogue shows the numbers in consecutive order 
and opposite each number, the amount of those parts found in a motor vehicle. 

The last part of the catalogue lists alphabetically the main parts of an 
engine and under each part the smaller parts that go to make it up, also giving 
the part number and number of parts in a vehicle opposite each name. In this 
Way the number can be found (either by means of the illustration in front or 
the index in back). 

Q.M.C. Form 160 is the blank form used in making these requisitions. It is 
a blanket form of requisition and is used whenever there is no special form 
covering a certain item required. It is a very simple blank which needs no ex- 
planation itself. Form Q.M.C. 160 is the first sheet, or outside cover, and the 
additional sheets that may be necessary are form Q.M.C. 160a. 

Instructions, Form M.T.C. No. 113 

Form No. 113 is used in connection with the repair of motor vehicles and 
shows the man's number who works on the job, his department number and 
the job number; also the date or various dates on which the work was done on 
the motor vehicle, the time that work was started each day, the time that work 
was stopped, and the total number of hours' work for each day. On the back 
of Form M.T.C. No. 113 are the instructions to the mechanics by the foreman. 

CMC 



Administration — Lecture II Page 2 



Exercise in Q.M.C. Form No. 160 

Using the parts catalogue for Class B Standardized Military Truck, make 

out requisition for the following spare parts: 

Part No. Name No. Required 

1073 Piston 1 

1010 Valves 2 

1011 Springs 3 

1099 Cam Shaft 1 

4251 Distributor 1 

1128 Gear 1 

1129 Gear 1 

4701 Battery 1 

4802 Head lamp 2 

6029 L.H. Arm front axle 1 

7201 Front Spring 1 

2509 Sleeve 1 

2508 Handle 1 

2505 Crank 1 

3401 Guard 1 

3032 Shutters 2 

3002 R.H. Side 1 

7361 Front Bumper 1 

8207 R.H. Plate 1 



CMC 



Administration — Lecture III Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ADMINISTRATION 

LECTURE III 

Forms From the Standpoint of the Mechanic 
Military Correspondence — Military Channels 

Forms 

Service Record. 

Personnel Report for Enlisted Men. 

Individual Equipment Record. 

Soldier's Deposit Book. 

Stolen Property Report. 

Delinquency Record. 

Records of Court-Martial. 

Honorable Discharge. 

Final Statement. 

The following is a brief description of the most important forms, from the 
standpoint of the mechanic, used in the administration of a motor transport 
company. 

Service Record (Form A.G.O. 29). — When a soldier is enlisted or reen- 
listed, a service record on this form is opened for him by the recruiting officer, 
who fills out the descriptive list, Prior Service, and the first part of the current 
enlistment. All other data called for will be filled from time to time by the 
soldier's company or detachment commander, and must be entered promptly 
and accurately. Each entry made under Military Record, Allotments, and 
Clothing Account, must be initialed by the officer making the entry. When a 
soldier is transferred or detached from his company, the company commander 
will fill out the proper indorsement and forward the Service Record to the sol- 
dier's new commanding officer. A copy of each indorsement will be kept by 
each officer forwarding a Service Record. Each indorsement will give authority 
for the change of station or status of the soldier, his character, and a full 
statement of his accounst at the time. 

M.T.C. Personnel Report for Enlisted Men (M.T.C. Form 130).— This report 
is to be used only in case of enlisted men in the M.T.C, and is to be forwarded 
to the Director, M.T.C. It shows the man's qualifications and experience. 

Clothing Record — Individual Equipment Record (A.G.O. Form 637). — One 
of these forms is made out for each man in the company and contains an exact 
list of his equipment both of quartermaster property and ordnance property. 
The soldier places his initials at the bottom of the column where items are 
charged to him, as does the commander of his company. This is done each 
time articles are issued to the soldier (not in exchange for worn out articles), 

CMC 



A.G.O. 


29 


M.T.C. 


130 


A.G.O. 


637 


Q.M.C. 


41 


M.T.C. 


111 


Q.M.C. 


509 


A.G.O. 


594 


A.G.O. 


525 


W.D. 


370 



Administration — Lecture III Page 2 

and each time the soldier turns in articles an entry to that effect is made on 
the form, initialed in the same way. 

The form itself is attached to the soldier's service record and becomes a 
part of it. The soldier is thereafter responsible for every item charged against 
him and must be able to produce them on demand. If he loses or injures them 
through neglect, he must pay for them. 

Soldier's Deposit Book (Form G.M.C. 41). — Any soldier may deposit with 
the quartermaster a sum not less than five dollars at any one time to bear in- 
terest at the rate of four per cent per annum on all sums on deposit for six 
months or more. A soldier's deposit book will be furnished to every soldier 
making such deposits; such deposits made to be* receipted for by the quarter- 
master and attested to by the company commander. The book is kept by the 
soldier and must be presented with his Final Statement for payment. It can- 
not be assigned or transferred, nor can the soldier withdraw the money until 
he is separated from the service. 

Stolen Property Report (Form M.T.C. 111). — This report will be made out 
in case of any article of M.T.C. property which has been stolen. Four copies 
will be made, the disposition being as follows: original and second copy for- 
warded to H.Q., M.T.C, the third copy to be turned over immediately to the 
Assistant Provost Marshal of the territory in which the property was stolen, 
the fourth copy to be retained as a record for the company. This record must 
be filled out and mailed promptly. 

Delinquency Record, Enlisted Men (Form Q.M.C. 509). — In the office of the 
company is kept a loose leaf file of this form with the name of each man on a 
separate sheet. Whenever a man commits an infraction of the rules, that 
fact is entered on the sheet. The purpose of it is twofold — first, to determine 
the punishment to be inflicted; thus a man who is a frequent offender will get 
a more severe punishment than a first offender; second, to be able to determine 
at a glance the character of the man for purposes of promotion or indorsement 
on service record in case of transfer. It therefore behooves every man to see 
to it that his Delinquency Record remains free from entries, for his own ad- 
vancement depends entirely upon it and every offense he commits is noted and 
remains a permanent blot on his record. 

Records of Court-Martial (Form A.G.O. 594). — A copy of all charges pre- 
ferred against men in the organization, Form A.G.O. 594, must be kept as a 
permanent record. It is prepared in triplicate, one copy is retained in the 
office appointing the Summary Court, one copy forwarded to the Adjutant 
General and the third copy returned to the company. It includes a statement 
of charges preferred with a record of the disposition of the case by the court- 
martial and is attached to the service record of the man. 

Honorable Discharge (Form A.G.O. 525). — An honorable discharge is given 
to every soldier discharged from the Army, when his conduct has been such as 
to warrant accepting him for reenlistment and his service has been honest 
and faithful. 

Final Statement (Form W.D., Q.M.C. 370).— The Final Statement is a 
statement of his account with the United States given every enlisted man on his 
discharge or furlough to the regular army reserve and is the voucher on which 
he is paid. It is made out in duplicate and both copies must be presented for 
payment. It contains a statement of clothing account, pay, deposits, etc. The 
soldier's immediate commanding officer will have the statement prepared and 
will certify to its correctness. No final statement is given in case there is 
nothing due the soldier, but a letter to that effect is given him. The soldier 

CMC 



Administration — Lecture III Page 3 

takes the final statement to the quartermaster for settlement. He may, if he 
desires, assign or sell it to some other individual, but this has to be done in a 
certain way, otherwise the assignment is invalid. The easiest way for the 
soldier to have his accounts settled is to take them directly to the quarter- 
master. 

Military Correspondence and Channels 

The mechanic in the Motor Transport Corps will probably not have very 
much occasion to write a military letter, but every soldier should understand 
something with reference to military correspondence and to channels through 
which correspondence and even personal communications must pass. Military 
letters are written in a certain specified way. They are addressed not neces- 
sarily to the person to whom they are to reach but generally to the commanding 
officer of the post or the unit to which the soldier belongs. The following is an 
example of a military letter written by a soldier requesting a furlough, which 
will point out all of the essential features of the letter: 

Training Co. 15, 

Camp Jos. E. Johnston, Fla. 

October 31st, 1918. 

From: Pvt. John Smith, 

To: The Commanding General, 

Subject: Furlough. 

1. It is requested that I be granted a ten day furlough, commencing Novem- 
ber 5th, 1918, for the purpose of being married. 

2. I have been in the Army since May 1st, 1918, and have never been absent 
for a longer period than twenty-four hours. 

3. I have sufficient funds to defray my expenses during my furlough. 

4. My address will be 410 East 19th Street, New York City. 

John Smith. 

A letter like the above will probably be prepared for the soldier in the office 
of the Company by the company clerk. It would then proceed through mili- 
tary channels, that is, first, it would be handed to the commanding officer of 
the company who would place upon it the first indorsement. It would then 
be forwarded to the commanding officer of the next higher unit. (At Camp 
Johnston, it would be the group commander). The next higher commander 
then indorses it and passes it on to the next higher commander. (At Camp 
Johnston the group commander would pass it on to the headquarters of the 
camp), where action would be taken upon it. 

When a letter is finally disposed of, it passes back through the same chan- 
nels it took on its way up. 

Military Channels are used not only for written correspondence but verbal 
communication too in the Army. Thus, if a soldier desires to speak to the 
commanding officer of his company, he must first obtain the permission of his 
first sergeant. The reason for this is that wherever possible it is desired that 
the higher authorities be protected from the necessity of doing a lot of extra 
work unnecessarily. In the case of the letter, if any of the intermediate com- 
manders through whose hands it passed had the authority to dispose of it 
finally, he would do so and thus save it from going to the Commanding Gen- 
eral, and so, where the soldier wants to speak to his company commander, if 
he first interviews the first sergeant, he may find the first sergeant can settle 

CMC 



Administration — Lecture III Page 4 

his difficulty, and thus the commander can devote himself to the more impor- 
tant matters, leaving the minor ones for the sergeants to settle. 

To the new soldier, all of this sounds like a lot of "red tape," but it has 
been found necessary by long experience in the Army for the purpose of get- 
ting efficiency. The reason why all the intermediate commanders must be 
aware of the nature of communications that pass from below up is because 
they are responsible for everything that happens within their command and 
must therefore be aware of everything that is going on. In this way the soldier 
will find that every rule in the Army has a reason behind it if he will only dig 
far enough to discover it. 






CMC 



Administration — Lecture IV Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
ADMINISTRATION 

LECTURE IV 

Allotments, Compensation, and Insurance 
Military Hygiene 

There are certain matters with reference to the Army and Army Adminis- 
tration that are important for every soldier to know, such, for instance, as the 
manner in which the United States Government has decided to protect the lives 
and future welfare of its soldiers. Most of you perhaps are already more or 
less familiar with allotments, allowances and insurance, but there are some 
features of these which require a little additional explanation. 

The War Risk Insurance Act passed by Congress in the summer of 1917, 
covers fully the entire matter of allotments, compensation and insurance. 
These are three distinct and separate portions of the act, none of them affecting 
the others in any way whatsoever. 

Allotments and Allowances 

Every enlisted man is permited to make allotments of any portion of his 
pay that he desires to any one. However, where the soldier has dependents, 
the Government knowing that pay of the soldier is inadequate for their support 
and his, has decided to add what is known as an allowance to the allotment, 
for the benefit of such dependents. This the Government will add only in case 
the dependents are related closely to the soldier and where the soldier has 
habitually supported them in the past. The dependents for whose support the 
Government will add an allowance, are parents, including grandparents, 
brothers, sisters and grandchildren, and the allowance given by the Govern- 
ment is in varying amounts from $10.00 for each parent to $5.00 for grand- 
parents, grandchildren, brothers and sisters, the total amount of the allowance 
being limited to $50.00. No allowance is made unless there is an allotment 
made by the soldier of at least $15.00 if he has no wife, and if he has a wife 
the allotment must be at least $5.00. The above allotments are known as Class 
"B" allotements, and are purely voluntary, there being no compulsion upon the 
soldier to make them. 

But, where the soldier has a wife, whether she is living with him or apart 
from him so long as there are no actual divorce proceedings separating them 
he is required to make an allotment of $15.00 per month to her, to which 
allotment the Government will add $15.00 as an allowance with additional 
amounts for children if there be any, and if the soldier has children, but no 
wife, he will be required to make the same kind of an allotment. Should the 
soldier be divorced from his wife or separated from her, and there be a court 
order granting her alimony or separate maintenance, the soldier will be re- 
quired to make the same allotment, and the Government will make an a'.low- 

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Administration — Lecture IV Page 2 

ance sufficient to meet the court order, and not exceeding $15.00, or the addi- 
tional sum where there are children. The only exceptions to the above rule are 
where the soldier can prove unfaithfulness on the part of his wife, or where 
the wife makes written affidavit that she is able to support herself and waives 
the allotment. 

Compensation 

The next feature of the act is the compensation feature which provides for 
the support of the soldier in the event that he is injured in the service of his 
country, or for his dependents in the event that he dies in the service of his 
country. In former wars what is known as pensions were given to soldiers 
and their relatives, but it was thought that the pension system had not proved 
successful and was capable of many injustices, consequently the compensation 
feature of the act was evolved, based upon workmen's compensation laws that 
have been enacted throughout the country in recent years. It provides for a 
graduated scale of payments to an injured soldier depending upon the extent 
of his injuries and the size of his family. In the event of his total disability, 
a certain amount of compensation is fixed, and where he is only partially dis- 
abled, a proportion of that amount is given to him, determined by his loss of 
earning capacity. 

Where a soldier is partially disabled, he will be required, however, to attend 
one of the vocational schools which will be established so that he again may 
make himself a useful member of society. The fact that perhaps he may be 
able to earn more after completing a course than he was before he entered the 
Army will not operate to reduce his compensation, for the idea of the 
scheme is solely to avoid establishing an indigent pension class, but the law 
provides that if the soldier refuses to take such a course, compensation will 
cease. 

In the event of the death of a soldier, compensation will be paid to his 
widow and children (if there be any) in certain specified amounts, and also to 
his widowed mother, but the total sum of compensation thus paid will not 
exceed $75.00 per month. 

Compensation applies to both officers and enlisted men, and in the event 
that the disability or death occurs either through sickness or injury, but it is 
required that the sickness or injury be suffered in line of duty. Everything 
is considered in line of duty, excepting: 

1. Where the disability existed before the soldier entered the service. 

2. Where it was incurred while the soldier was absent without leave. 

3. Where it was incurred by the soldier's own immoral conduct. 

Insurance 

The last feature of the act provides for the insurance of soldiers against 
death or total disability. When the war broke out commercial insurance com- 
panies immediately placed a ban upon insuring the lives of men of military 
age. Life insurance in recent years has become almost a universal matter. 
Practically every young man when he becomes of age, and before, takes out a 
policy of some kind and usually increases the amount as his earning capacity 
increases. Realizing this fact, and the further fact that many men would be 
precluded from taking out life insurance because of the risks incident to the 
service, the Government decided to go into the insurance business. At a re- 
markably low rate, then, the Government furnishes this insurance to the offi- 

C M c 



Administration — Lecture IV Page 3 

cers and men in its service. It can afford to do this because it seeks to make no 
profit and it eliminates the enormous overhead expense that insurance com- 
panies must meet, such as large offices, and commissions to innumerable agents. 

Insurance may be taken out by any person in the military service within 
one hundred and twenty days after entering active duty. It may be taken 
out in multiples of $500.00, the smallest policy being $1,000.00 and the largest, 
$10,000.00. The premiums are deducted from the man's pay each month. 

The Government has provided further that the insurance shall continue 
throughout the war and for five years thereafter provided the premiums are 
paid. Within five years after the close of the war, the soldier may transfer 
his policy to any of the commercial insurance companies, changing it into any 
of the recognized forms of insurance policies. 

This insurance is an out and out business proposition between the Govern- 
ment and the men. The policy is paid in the event of the death or total dis- 
ability of the man whether that occurs in line of duty or not. 

Military Hygiene 

While on this subject it might be well to say something with reference to 
hygiene and the care of the person. From time immemorial, the soldier has 
been known to be methodical, neat, spic and span. It is necessary that every 
one should be so, and particularly the soldier, for he is the representative of 
his country, and as he reveres his country so he should endeavor not to reflect 
discredit upon it by being dirty, slovenly or unhealthy. 

To the average American, little need be said upon this topic, for the stand- 
ards of health and cleanliness in the United States are very high. However, 
a little resume of the requirements of the Army in this particular would be 
appropriate. 

The army requires in the first place that every soldier keep himself scru- 
pulously clean, aside from the matter of appearance. This is important to 
the Army, for cleanliness means health and health means "pep," and pep means 
efficiency, and efficiency means success — that last is what we are here for, and 
what we all want in the shortest possible time, and if the soldier will but look 
at it from this standpoint, he will be inclined to be more in sympathy with 
hygiene rules, which otherwise he might think an imposition. Briefly, the 
soldier is required to keep himself neat at all times; his shoes polished, his 
clothes clean, his hair neatly trimmed, his face cleanly shaved. Army Regula- 
tions require that every soldier bathe at least twice a week. Sufficient clothing 
is furnished the soldier so that if he is at all clean in his habits he may also 
have fresh clean clothing to wear. Local health regulations established at the 
various camps by the Medical Department require that certain care be taken 
with reference to spitting on floors, care of latrines, washing the hands after 
using the latrine, washing the hands before meals, use of individual mess 
equipment, brushing the teeth, etc. All of these things have their purpose in 
guarding the health of the Army, as the soldier will readily see. 

The mechanic working in a shop or in the field, on grimy, greasy, oily motor 
vehicles is sometimes prone to think that these regulations do not affect him. 
It is true that if is more difficult for the mechanic to keep himself clean, than 
perhaps the clerk or some other soldier, but it is none the less important. 
While at work, it is true, the mechanic's face and hands will always be grimy 
and greasy, but he should endeavor to restrict the grime area to his face and 
hands. General Orders provide that work such as mechanics do shall not be 
performed in the prescribed uniform but that denim clothing shall be worn; 

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Administration — Lecture IV Page 4 

therefore, it should be an easy matter for the mechanic to always have a 
clean uniform when away from his work. Since only his arms and face are 
exposed while he is at work, there is no reason why he should not keep the 
rest of his body clean at all times by bathing frequently. Though it is im- 
possible for him to keep his face and hands clean in the shop, he should keep 
them clean at all other times, because dirt breeds germs, and germs cause 
disease. 

As regards the other regulations concerning health, there is no reason at 
all why the mechanic should not live up to them absolutely. There are only 
a few of them; it is easy to remember them, and the reward for observing 
them is health and vigor. 

Diseases are transmitted in five ways: 

By breathing germs (colds, pneumonia, consumption). 
By swallowing germs (Typhoid fever, ptomaine poisoning). 
By touching or coming in contact with germs (Boils, ringworm, gonor- 
rhea, syphilis). 

By having germs stuck under the skin by bites of insects (Malaria, 
and yellow fever) . 

By heredity (Insanity and syphilis). 

Not considering the last means of becoming diseased, which no one can 
help, the first four are absolutely preventable. The first consideration is to 
keep oneself clean, strong, and free from dissipation. It is a known fact that 
a person who leads a clean, moral, healthy life, is able to combat the germs 
of disease even if they get into his system, for the normal action of the blood 
is such as to overcome these outside bad influences, but when the system is 
weak and run down from dissipation or immoral excesses, it is unable to meet 
the added work put upon it by the entry of disease germs, and the person 
falls a victim to them. So too, in the case of injuries or wounds received that 
are not preventable, the man who has led a clean, normal, healthy life is by 
far better able to resist the effects, and his constitution will almost guarantee 
his recovery. 

The Army protects you in advance against most diseases — you are inocu- 
lated against typhoid, your food is supervised and inspected and kept per- 
fectly clean and fresh, so that you do not swallow germs; regulations with 
reference to your sleeping quarters, provide that each man has ample space 
to give him fresh air, and that the barracks be properly ventilated so that you 
do not breathe germs. Your barracks are screened and the low swampy places 
within the vicinity of the camps are drained to keep off mosquitoes so that 
germs cannot be injected into you in that way. As to touching germs, that 
depends entirely upon you. You would not willingly touch a running sore, 
or sleep in the same bed with a person having a contagious disease, because those 
things are visible to you and you are afraid of them. Associating with loose 
women and forming immoral habits are far more dangerous because there is 
nothing visible and you are not afraid ; but the results are much more harmful. 

Much has been said upon this subject and, therefore, need not be repeated 
here. Be men, exercise your wills, keep away from temptation, lead clean, 
healthy lives, and you will never have cause to regret it, and at the same time 
you will be good soldiers conducting yourselves the way Uncle Sam wants 
you to. 

The Prophylaxis Stations are established not to condone your offense, but 
to try to prevent the consequences of the acts of the weak ones among you. 

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Administration — Lecture IV Page 5 



If you are too weak to resist temptation, the Articles of War provide that 
you will be punished if you did not visit a prophylaxis station, but if you did 
visit the station and the treatment was unsuccessful, the disability that you 
sustain is still not in line of duty. You will receive no compensation for it 
if it is permanent, and you will receive no pay while you are being treated 
for its cure. 



<: M o 



Administration — Lecture V Page 1 



MOTOR TRANSPORT CORPS 

EXECUTIVE DIVISION — TRAINING BRANCH 

Company Mechanics' Course 
FIELD SERVICE ADMINISTRATION 

LECTURE V 

The Mechanic as a Soldier, and Military Law 

It is sometimes hard for men who are engaged in some of the necessary 
work of the Army, outside of fighting, to realize that they are just as much 
soldiers as the man who shoulders a rifle, and defends a trench. But the 
Army consists of a great many men from all walks of life, doing all sorts of 
duties; nor is a man any less a soldier because he is in the Quartermaster 
Corps, or carries a stretcher, or is a hospital attendant, or drives a motor 
truck, or repairs motor vehicles in some repair park. All of these men go to 
make up that magnificent thing — our Army, and they are vitally necessary 
for our Army's welfare. To bring it right down to the mechanic, the soldiers 
in the trenches would be helpless in the fight if their supplies and ammunition 
and reinforcements were not constantly streaming to them in a never ending 
flow. To get these things to the trenches requires trucks, but to keep the 
trucks in shape so that they are able to perform their work requires mechanics, 
and good mechanics, who are also good soldiers. Illustration can be carried 
out in this way to cover every branch of the Army, but that is unnecessary, 
nor have we the time to devote to it. It will be seen from the foregoing that 
the mechanic is an integral and vital part of the fighting army. He is a soldier 
in every respect and consequently he must conduct himself like a soldier at 
all times. 

There are rules and regulations made for the government of the soldier 
which must be observed at all times. In the preceding lecture we cover rules 
concerning the health of the soldier. It was pointed out that it was important 
to preserve the health of the Army because upon that depended its ability to 
perform its duties. The average American accustomed to a more or less easy 
independent existence, governing himself generally by the dictates of his own 
mind, while a law-abiding citizen, it is true, nevertheless is very much self- 
willed. We pride ourselves upon that fact. We depend upon ourselves — 
we do not follow in the beaten path, and as a result, we have what has been 
called Yankee ingenuity. 

To a person of this sort suddenly taken from this independent sort of life, 
and thrust into the Army where everything seems to have already been de- 
cided for him, and his whole course of action throughout the day is fixed, some- 
times these rules and this system seem a little irksome, and sometimes we 
find that a man who is a law-abiding citizen in civilian life breaks the traces 
time and again in the Army and gets to be what is termed "hard." Occasion- 
ally such a man is incorrigible, but in by far the majority of instances, it is 
just because he has not understood the reasons for all of these things, and. 
no one has explained them to him. Just as there is a reason for military 
channels, just as the science of medicine is a reason for all of the health 
regulations, so there is a reason based upon years of experience for all rules 

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Administration — Lecture V Page 2 

of the Army. In civilian life you do not salute your employer, you do not 
come to attention when he speaks to you — perhaps you do not obey to the 
letter instructions that he may give to you, or perhaps you are inclined to 
argue as to the expediency of a suggestion of his, but that is civilian life. 
If you do not obey your employer, if you do not carry out instructions, per- 
haps he may lose money and you may lose your job, but that is about the 
extent of the injury that you can inflict by such action. The reason is that 
in your employment the object of the business is to make money. In your 
present employment, the object of this business is to fight — to kill as many 
of the enemy as is possible with the least loss possible on your own side. The 
thing that you are dealing with is not your job or your employer's money 
(because you will find it is very difficult to lose your job in the Army) , but 
you are dealing with the lives of your comrades — in a large way with the 
lives and happiness of your family and the families of your comrades, and in 
the ultimate analysis with the liberty, the happiness and privileges that your 
government affords you, for you are defending your government and your 
country. These are the things that are involved, and that is why you cannot 
stop to argue or take it for granted that your method of doing things is a 
better one than your commanding officers. The Government has seen fit to 
impose a confidence and trust in your commanding officers by reason of the 
fact that they have demonstrated their ability. It is your duty as a man, as 
a loyal citizen, and as a good soldier to respect that authority. The mechanic 
might say "Well, that might be true of the man in the trenches, that lives 
depend upon his strict obedience, but I am working in a shop." Let him not 
forget the opening paragraph of this lecture, that he is every inch a soldier, 
no less than any other man in the Army. The very structure, the very 
fabric of the Army depends absolutely and entirely upon strict obedience. 
Paragraph I of Army Regulations says "All persons in the Military Service 
are required to obey strictly and to execute promptly the lawful orders of 
their superiors." The Army must move swiftly and surely without doubt or 
hesitation in order to be successful and there is not time always to explain 
the reason for any particular move. The man below must take for granted 
that the man above knows what he is about and must execute faithfully and 
without delay, to the letter, his orders. 

"Well," says the proud man, "I am willing to obey to the letter and can 
realize the necessity for it, but why must I salute my fellow-man and per- 
form all of the menial things that I am required to perform, just because he 
is an officer, when the Declaration of Independence says all men are created 
equal." The salute is not a mark of servility; it is not humbling oneself be- 
fore a superior man. The good soldier is proud to perform it. He comes to 
attention with a snap and executes the motion with pride and in a strictly 
military manner, for, in the officer he sees not his superior as a man, but a 
person in whom the President of the United States has entrusted authority. 
He is saluting not the individual, but the United States Government behind 
that individual. From ages back the salute has come to us as a distinctive 
mark of the military service. It is exchanged between military men and in- 
dicates to all that those persons performing it are brothers in arms. It must 
be remembered that it is just as incumbent upon the officer to return the sa- 
lute as upon the man to give it. It indicates the comradeship in the profession 
of the sword. 

And, if officers are not permitted to mingle upon an intimate basis with 
the enlisted men it is not because it is deemed the enlisted men are inferior, 
but because familiarity breeds contempt, and in order that that strict obedi- 

C M c 



Administration — Lecture V Page 3 

ence that is necessary for the welfare of the Army be performed the officers 
must keep themselves somewhat aloof from the men. 

It is unnecessary to go into any further explanation of these things. The 
average American with his high intelligence and good understanding will 
realize them, and realizing them is what makes the discipline of the American 
Army, which has already proved and will prove, in the future, to be so far 
superior to some other disciplines, notably that, for instance, of the German 
Army. Their discipline is the discipline of fear imbedded and implanted in 
the men. A blow in the face, a smack with the flat of the sword, a kick, are 
common things for an officer in the German Army to bestow upon the soldier. 
The latter takes it as of right because he is accustomed to that sort of dis- 
cipline, and he marches into the battle and obeys orders because he is afraid 
and because his officers stand behind him with drawn pistols. That discipline 
of fear has broken down before the American discipline of conscience. Our 
officers lead our men into the battle, and Army Regulations, Paragraph 3, 
provide that "Superiors are forbidden to injure those under their authority 
by tyrannical conduct or by abusive language." It is because our men are 
intelligent men and realize themselves the necessity for discipline that we 
can do this, and while the other discipline breaks down when the officers are 
not there to drive the men forward, ours causes our men to strive all the 
harder if their officers should happen to be disabled. 

But, for those few men who are not willing to obey and be good soldiers, 
there are the Articles of War and Military Law, and the power of the Army 
behind them to enforce them, and offenders against Military Law are punished 
in accordance with the degree of their crimes by courts-martial. There are 
three kinds of courts-martial, General, Special and Summary. The first con- 
sists of from five to thirteen officers, and has power to try all persons in the 
military service for any offense committed against Military Law, and can 
inflict any penalty allowed by the Articles of War, including death. The 
Special Court-Martial consists of from three to five officers and has power 
to try all persons in the military service, except officers, for any offense 
against Military Law, excepting such as is punishable by death. It can inflict 
any punishment up to six months' imprisonment, and six months' loss of pay, 
but cannot sentence a man to be dishonorably discharged. The Summary 
Court-Martial consists of one officer; it may try all persons in the military 
service, except officers, for any offense committed against Military Law not 
punishable by death; and can inflict a penalty not to exceed three months' im- 
prisonment and three months' loss of pay, but cannot sentence a man to be 
dishonorably discharged. A noncommissioned officer may object to a trial 
by Summary Court-Martial, but will be required to submit to it provided he is 
ordered to do so by an officer competent to bring him to trial before a Gen- 
eral Court-Martial. Both Special and Summary Courts-Martial may reduce 
noncommissioned officers. 

Generally, the way things work out, minor offenses are tried by Summary 
Court-Martial, more serious ones by Special Court-Martial, and the very grave 
crimes by General Court-Martial. 

The courts-marital are the criminal courts of the Army which enforce the 
laws of the Army — Military Law. They are established for the purpose of 
punishing offenders and their punishment is swift and sure, but, very fre- 
quently, as in civil life, it is found that a man is accused of a crime, but is 
in fact innocent. Every opportunity is given by the courts to a man to defend 
himself. He is provided with counsel free of charge, that is, not a civilian 
lawyer (though he may procure one if he desires at his own expense) but he 

CMC 



Administration — Lecture V Page 4 

may request for his counsel any officer at the post, and that officer will be as- 
signed to him if he can be spared. In any event his interests and rights are 
protected; he is presumed innocent until proven guilty; he is presented in 
ample time with a copy of the charges against him; he is acquainted with his 
rights by the Judge Advocate; he is confronted (in capital cases) with his 
accusers; he is given an opportunity to cross-examine the witnesses opposed 
to him; he may testify in his own behalf or may refuse to do so if he desires; 
he cannot be forced to testify against himself; he may make a statement to 
the court in his own behalf, and in many other ways he is given every oppor- 
tunity to defend himself. 

One more thing is important for the soldier to know with reference to Mili- 
tary Law. A great many soldiers seem to get the impression when they get 
into the Army that they are immune from Civilian Laws — in other words, 
that thereafter the Army will protect them in the event that they have a 
"run in" with Civilian authorities. This is absolutely wrong. The Army 
never intends and never has done any such thing. On the contrary instead 
of losing the jurisdiction of Civil Courts by entering the Army, what the 
soldier in fact does is to assume new obligations, the necessity for obeying 
the Military Law also. The Army wants none but law abiding citizens and 
does not seek to protect a man who breaks the law of the community. 

However, if the soldier will conduct himself in a proper soldierly manner, 
and will conform to the spirit as well as the letter of the Articles of War he 
need never have occasion either to get in trouble with the Civilian Authori- 
ties or to test for himself the justice meted out by courts-martial. 



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